I think you should be the one to make the judement and

decision. And I do understand your mom's aspect. She is just like any other mom in this world, wants the best for her daughter. But after all, this is your life and your future. So, I agree with riley, try to be nice to your mom, but don't tell her too much negative news of your boyfriend. If you don’t want to hear too much criticizing from her

From what you wrote in the post, it seems that it is still lack of communication between you and your boyfriend. It is very odd that he asked for looking at your diplomas, and it is equally strange that you wanted to talk to his ex-wife to find out more about him. I think that you and he should exchange thoughts and points of view much more often. A relationship should build in a foundation of mutual trust and mutual respect