Weddingbee boards

Hi all! I've been a long time lurker on the bee boards and I've posted here and there in random threads, but this is the first thread I've started. Sorry this is going to be a long one...

Unfortunately, I'm desperate for advice. I'm having trouble with a bridesmaid who seems to have fallen off the face of the earth (except on Facebook). This particular young woman (who will be referred to as J from here on out) has been a friend of mine for about 6 years now and I was a bridesmaid in her wedding two years ago.

The bridesmaids picked out their dresses for my July 2010 wedding back in November. One of my bridesmaids ordered her dress on the spot and the rest agreed to order their dresses before February (a deadline they came up with themselves... I had nothing to do with it). Mid-January, I called all of the girls and told them that I was willing to help a little with the cost of the dresses since I knew their ordering deadline was coming up. J told me not to worry about it that she had it covered and she would order her dress soon.

Well, the bridal shop called me mid-February to tell me that J was the only bridesmaid who had not ordered her dress and she needed to do it before February 26 or she would have to pay rush fees. I called her to relay the news. She, once again, said no problem, she had it covered.

I called the bridal shop yesterday (obviously past the deadline) and bridesmaid J has still not ordered her dress. Luckily, I told the bridal shop to order the other girls' dresses  and not wait for J. Thankfully the other girls will not be paying rush charges because of J's lack of action.

Now here's my problem. I have tried to call J to see if she's okay or if there's anything I can do to help, etc but she's not returning phone calls. She has left me random notes on my FB wall that have nothing to do with the dresses, which leads me to believe that it has nothing to do with her being angry with me for some reason. Basically, I have no idea what is going on and she's not returning calls.

I'm frustrated because I didn't do this to her when I was in her wedding! I ordered my dress in a timely fashion and I was as helpful and available as I could be. My mom thinks I should just send her a message and tell her that she's being replaced since she obviously doesn't care enough to be a part of the wedding and she's too late on the dress. I don't know how I feel about that. I understand where my mom is coming from. She thinks I shouldn't worry about sparing her feelings since she is showing such little respect for mine, but I don't know. That just feels really harsh to me.

How do you think I should handle this situation? Should I replace her (I have a friend who volunteered to step in if J flaked)? Or should I try to give her another chance? I just don't know what to do...