Just because he's engaged and married doesn't mean he's not grieving and he may not even be happy. Everyone handles things differently so while you need to be alone, he may have found comfort in someone else, and just decided to marry her so he wouldn't be alone....

Sometimes after a breakup we want someone back just because we don't have them anymore, not because it was a really good relationship.

I know it's hard. i hope it gets easier for you soon.