She wants me to be her matron of honor?

I think its very adult of you to have made her a bachelorette basket given the events that happened at your wedding. I don't see what harm it would be to stand beside her for 10 mins tops. If that long. However, you do need to talk to her about it. She should've asked you. Yes she is sort of using you, but in this situation just be the bigger person, someday your favor will be returned. Maybe not by her but probably by someone else. Hope this helped