Uninviting a groomsman... repost from BHB.

The first person my FH asked to be a groomsman was a friend we have known for some time and used to spend a lot of summer days and nights hanging out with. He recently went to Texas for grad school so we have lost contact and he has regressed in maturity to acting and thinking like a 20 yr old frat boy instead of a repsonsible and respectful 27 yr old. He has been unsupportive and rude to us this past summer and he and I had a little fall out over email. He attended the engagement party we all went to for one of our friends and he got drunk and threw 2 glasses over the balcony onto the parking lot where guests and parking attendants were standing. This behavior really had us concerned.
When my FH spoke to him over the phone back in august to tell him we had switched our wedding date, he had no idea why my FH was suggesting he had to wear a tux to our wedding. He 'forgot' we had even asked him to be in our party last March! How the h*ll do you forget you have been asked to be a part of a friend's wedding?! My FH was PO'd and told him that if our wedding was of so little importance and he didn't care enough to remember that he could back out, but unfortunatley he didn't. They got off the phone and ever since then we have been trying to figure out a way to tell him forget it.
Anyone have any experience or advice with this situation