No, it’s not good. If the girl cheated on you and, at the same time, is mentally unstable, then we recommend that you don’t even try courting her as it’s not worth it. In fact, when it comes to “get my ex girlfriend back” and cheating, it’s even best not to attempt anymore because she hurt you and not the other way around. If there is a need to court again, she should be the one courting you if she wants you back. Don’t even ask yourself if you want to “get my ex-girlfriend back” when she’s the one who ruined your relationship. Show her that you have moved on after the break-up—let’s see if she does not come back.