This is just my opinion, but he's lying to you about the fact that Mom is mad at him, and so is the whole family and no one is talking to him. Now what does your GUT really tell you? My gut says that it was all a line of BS just so HE can make you feel bad this time -- just so HE can get some sympathy. Is that his usual "MO?" Well, if it is, he's right back to doing it again.
I don't think I'd believe a thing he said again.

If he couldn't be honest about something as simple as this issue (him coming to a wedding) then what about the important things? Are you going to be able to believe him about those? Heck no.
Sorry my friend. I know you don't want to "write off" your brother, but I don't think you have any other choice, for the safety of your family! God bless & keep us posted, will you? Hugs, Lee