Why should it be you that has to transfer?

He is the one who dumped you for a mutual co worker and now he thinks everybody is supposed to be friends? Why are you being so accommodating and understanding to this turd?

Chances are he is being nice to you so you can be his "back up plan" if it doesn't pan out with the new one.

You should be relieved that you didn't marry him. If he screwed you over he will probably do it to her as well. Are there any other women at your school he could hook up with to complete the trifecta?