May I suggest that Tom didn’t end things with you, he ended things with himself, first.  Stepping into the shadow of a skilled manipulator can definitely do that to a person. If he didn’t have himself as he knew himself, then he couldn’t have you. Does that sort of make sense?  Unfortunately, she isn’t the one responsible. He made his adult decisions. 

He is not the same person you once knew. He has a new behavioral and emotional skill set that you don’t want to expose yourself to unless you want an ongoing complicated life. You can’t save him from himself. Don’t try. Don’t get looped into it. 

I’m sorry this happened to you. People can be jerks.