That sucks, I'm sorry you're having to deal with that!
My mom (out of NO where, and who is my bestest friend, hands down) one day freaked out at me saying things about I am close with Doug's mom (who is a major over-achiever and loves to take control of things, like its HER wedding! but in a friendly way) and maybe I should ask her, blah blah blah, how Doug's mom is doing so much for the wedding, maybe Doug's mom knows...
I realized that for whatever reason she was feeling over-emotional about the whole wedding thing and it just manifested itself in that form of jealousy. I was so shocked I didn't even know what to say to her! I apologized profusley even tho I had no clue what I was really apologizing for, and the next day I started to give her little tasks, things that she could help with and stuff to make her feel like she was contributing more than just $$.
I've actually used this tip on a few people involved, asking them to do something or find something that I need, including Doug! I think everyone wants to be involved in any way, and we just need to find something they can do to make them feel lke they are needed, even if they are far away from us. It worked with my mom, and now she is totally into the whole thing, she likes knowing that she is helping and it amkes her feel more involved.
Good luck!