OCD, you know how this is going to go.
A confrontation is inevitable, and you avoiding it and trying to just bounce out of her life like some mic drop isn't badassery, it's cowardice. I know the emotions are high. The anger, the betrayal, and you are deep in that emotional muck, believe me, I've been there, but avoiding talking to her isn't the best move.
Putting it off tomorrow is only going to put you on the defensive. Why? Because you'll confront her tomorrow, and she'll counter with, "You knew since yesterday? Why are you bringing it up now?" and then you'll have lost control of the conversation, because you'll be fumbling for a response as to why you sat on this for a full day before talking to her about it. You're being super passive aggressive right now, and that's just not a productive way to get out of this relationship as cleanly as possible.
Talking to her isn't to try and repair things. It's to lay out what is going on, why it's happening, and to express in no uncertain terms that you're through with this relationship. You can hash out the rental lease agreement tomorrow as planned, but there's literally no point in trying to "hurt her" as you put it. Think about it this way. If you confront her now, handle your business tomorrow, then leave, when her friends or anyone else are asking what happened in the relationship, and she tells them why, what's going to hurt her the most is that her friends or family, are going to be siding with you. Because you didn't act like a baby and try and get her by just upping and leaving with no warning. That's petty and immature.
Thoughts of revenge feel really good in the moment, but anger fades, and in the end, both of you will be looking like jackasses if you take the route of avoiding confrontation and just leaving.
I've made the mistake of going to be angry. Fuming over something my wife said or did that upset me, but tried to wait until the next day to confront her about it. It doesn't feel good. Over the years, I learned to be upfront about what was bothering me, and telling her straight up. And she does the same. We've been together 13 years, married for 7, and while we don't really fight (maybe 2 times a year, tops), and both of us hate confrontation, we always talk about our issues. I'm not perfect. Neither is she. The point I'm trying to make isn't to get you to stay with your girlfriend. God no. That's done. The relationship is over. But the point is to express that avoiding the inevitable isn't the best option.
I mean, you're going to go to bed upset whether you talk to her or not. You're going to go through your work day tomorrow upset whether you talk to her or not. The relationship is over whether you talk to her or not, but why go to sleep with the burden of what you know on your shoulder while she is oblivious to your pain? The goal isn't to hurt her, but to start the process of healing and getting over the relationship sooner rather than later.
I wish you the best, but in the end, you want to be coming out of this looking better than her. She already fucked up by cheating. You handling it like an adult and being responsible is the best form of revenge. Talk to her. Tell her it's over. Hear what she has to say. Find out about your lease agreement. Then leave, and never talk to her again. It'll eat her up that she can't throw anything you've done back in your face. She got busted fair and square, and she knows it.
It feels good when word from the grapevine comes down, and her friends and family think you were in the right.