I know that you've compared your relationship with your exT to my current, and so reading this makes me hurt for you. I couldn't even imagine how I would react if something like this were to happen to me, knowing how attached I am to him.

I would definitely recommend discussing all of this with your current therapist. You were in a proximity relationship with someone who you believe deceived you and rejected you. If you're hypothesis is right and we are twins, then this probably mimics situations that you've had with other relationships in your life. Use the hurt to really, truly heal.

I'm a PM away if you need someone to vent to.