How can i ever forgive her, would you?

I don't think you're overreacting. You've got a lot of reasons to be angry and feel let down by her, i'd be extremely disappointed too. But i do believe there will probably come a time where she realises how unfairly she treated you and may apologise, this will come when she is ready and truly feels remorse. It should be the same for you, even though it's part of therapy, you will forgive when you're ready and truly accept her apology (or even with no apology.) The process is to give you closure, don't tell yourself that you forgive her unless you mean it. Goodluck, hope everything gets better.