Relationship advice 101:
If you have to resort to her proving herself guilty, you won't be happy with anything else. In other words, even if she's actually innocent of whatever you're trying to prove her guilty of - your mind is set on her being guilty, no matter what the truth is.
So...
If she's really innocent, she'll forever be guilty in your mind - which means you'll probably have hard time trusting her. If you can't trust your other half, you can either work on repairing the relationship, or move on.
If she's really guilty, she's guilty. Period. If you can't trust your other half, you can either work on repairing the relationship, or move on.
End result is the same. You don't need proof - all it will do is feed the negative feelings which is not what you need right now. You need to decided what is best for you long term. Because there are only a few options:
1) She's guilty, you guys work it out, and move on together.
2) She's innocent, you guys work it out, and move on together
3) She's innocent, you think she's guilty, nothing can change your mind because you've decided she's guilty. Split, move on, don't hang on to the bitterness
4) She's guilty, you can't/don't want to work it out. Split, move on don't hang on to the bitterness.
Really it comes down to you. Either work it out or don't. But what you're doing is going to hurt you and her very deeply in the long term. I suggest a different course of action. It's true what they say - holding a grudge is like drinking poison thinking it will kill the other person. In the end, only YOU are responsible, both for your actions and your REactions.
And you don't need an app for any of this. Just some alone time sorting out what you really want - regardless of feelings or wanting to hurt her back for whatever wrong she may (or may not) have done.