A senior manager keeps tabs on everything and tattles on me

Holy shit! While I admire the ruthless hardball nature of bruce's idea in a theoretical sort of way, that's something someone with 30 years' worth of credibility can get away with. And even then, only if you're DAMNED sure the fallout is going to come down on her side and not yours. That's skipping a whole lot of steps in the escalation game and going unnecessarily nuclear right off the bat. That's extremely poor conflict resolution skills. If someone with only a few months and still on probation essentially threatened to burn my company to the ground over some minor interpersonal friction, they'd be out the door so fucking fast... (even if they did have a point in there somewhere.) You probably want to stick with one of the lesser options.

I just want to add that you probably grew up with some notion that "if you work hard, you'll keep your job and be rewarded" and that is not true in almost any work setting. Text books and HR theories are written as if that's true, but that's just the text. The SUBTEXT is important here, both in your actual job, and in your chosen career. Assholes are going to expect HR to abide by their UNSPOKEN racist hiring policies. Workers are well aware (especially low paid workers) that getting along means not so much "do your job well" but "abide by the SUBTEXT." Skilled HR types are those who can recognize subtext and strategically employ the text of HR rules and regulations (and employment law) to either do good (for the most vulnerable workers) or do bad. You want to find a skilled mentor working for a good company -- or you'll drive yourself crazy. Anyone walking into a new job should immediately start trying to understand the subtext and unspoken rules.

What vitabellosi said +1, but also: Some situations are better to let play out on their own, but this is not one of them. This is a situation where you want to be the one steering the bus. That's not to say get hostile with Betty. Don't do that. But you do need to be the one going to YOUR supervisor, with humility, saying "I don't understand why I can't seem to get along with Betty. I'm trying really hard, and what I'm doing seems to be working really well* with the other managers. Do you have any advice for me?" After that, before you have any interactions with Betty, run it by your manager first. "So, Betty owes me a new hire schedule, and I need to ask her about it. I intend to send her this email, what do you think?" You need to do this often, not just as a reaction to one of Betty's complaints. *this slyly (or not) includes a positive factual thing about yourself every time you're talking about a negative thing (the Betty situation.) Lest anyone forget the important thing. It also highlights that somehow Betty is different than the other managers. This works. It might also help to not ask Betty about things she owes you. See what your supervisor thinks of this idea: Send out a weekly impersonal mass email titled New Hire Process Status. List everything everyone gave you or needs to give you for the whole week, with a column for "received" or "not received." Give 'em some colors, managers love colors. Make overdue stuff red. It will piss her off mightily, but there won't be a damn thing she can say about it because it's not singling her out. It's just the facts.

Document everything and keep quiet about it unless you need it.

Well...it depends on whether or not Betty has the authority to fire you. Like others have said, it's probably recognized and accepted that Betty kind of sucks at her job. But she's not going anywhere. The concern is whether or not she can get rid of you. If she can, well then...I'd wait to see what happens after the probation period. If you're not fired then, it's probably not going to happen. If she can't, you want to accept that she's a pain in the ass, accept that this is what most work situations entail (there's a Betty-equivalent everywhere), minimize your contact with her and try to keep communication factual and via email only, and try to learn how to be an awesome employee as you appreciate everything Betty teaches you about who not to be at work. Believe it or not, Betty is giving you valuable lessons. Lastly, sure you can document away. I find it to be counterproductive. You're new; it's much more likely you'd be let go rather than Betty and ALL that energy you put into proving where you were awesome and she sucked...none of it will matter when you're looking for another job. There are Bettys everywhere. Don't let them drain the life from you.

Sorry you are going through this. I would let Betty deal with you through your supervisor if that is what she prefers, since it gives you another witness to her behaviour. Also, try to interact with her in writing whenever possible and copy your supervisor on anything you send to her. If you are accused of anything you did not do, especially if it is in writing, document your side of the story and send it to your supervisor. Then, keep on doing a good job, and try to build/keep good relationships with the other managers. It sounds like Betty is in over her head and looking for someone else to blame. The people around you will catch on soon.

For future reference, once a manager's behavior becomes a pattern (ie, two times of forgetting to do something for a new hire), that's when you bring your supervisor in. This is because 1. your supervisor is more likely to be able to get results from someone like Betty and 2. it protects you in situations like this. Don't feel bad about it, that's what supervisors are meant to do. And actually, it can make your supervisor trust you more, which is always a good thing. In this situation, I do think your supervisor has a point about trusting Betty to do her job. Not because she's trustworthy, but because there's only so much you can do. You can only do your job - you can't make other people do theirs. Knowing this is very important for surviving and not going crazy in the working world. But if there is a pattern of someone else not carrying their own weight, document the hell out of it, and make sure your boss knows. It sounds like you work for some sort of agency, government or nonprofit? In that case, I personally think it's unlikely that you'll be fired over this, though of course it could happen. Also, I'm sure you're not the only person who's had problems like this with Betty.

If you want to keep your job, and your situation is as precarious as you describe, you're going to have to swallow some of your pride and treat her like a friend/mentor who wants you to succeed instead of like an enemy. When you see a person as an enemy, it bleeds over into your body language and probably your email language, whether you're aware of it or not. And if Betty is as paranoid as she sounds, she's probably really good at picking up on unspoken challenges. So, ask for her help. If you're worried she can tank you, go to her and say your boss told you about her email, and you very much want to do better. Say it non-confrontationally. Say it like you believe that her concerns are at least partly valid, because it's possible that's even true. Nobody is perfect, and in her mind she may be using some actual newbie mis-steps as justifications for getting rid of you. Say you're really concerned that you're not communicating well with her (emphasis on YOU not communicating well) and that you would love to sit down and talk to her about how you can work together better. Let her know you're eager to stay and learn the system. Say that since she's been there for such a long time, you know there's a lot she can teach you. Basically, show her your belly. A person like Betty probably operates on a system of allies and enemies. Make it clear you want to be her ally, and she'll probably start liking you. Plus, it's really hard to dislike someone and help them at the same time, so by asking her for a favor, you may be able to switch yourself over in her head from challenger to collaborator. It may be hard to swallow all this when you do it, but it will make dealing with her in the future much easier. You'll be able to influence her far more if she sees you as "on her side" than if she sees you as a rival. More flies with honey, etc. etc. etc.

That is, show that you recognize and own the conflict, you want to and are actively trying to find a solution. The one who's playing defense is often seen as the person who "doesn't work well with others."