... Am I the only one that thinks you should have politely bowed out of the wedding party at or around the same time after you told the groom that you could no longer be his friend at all? Of course the bride is siding with her groom. Of course she is taking his side. She is marrying him! Just because she didn't directly say anything to you does not mean she didn't want to get involved. It just means she chose the super passive route in basically unfriending you.

OP - I am sorry you are in so much pain. I am sorry you did not realize this earlier. It is very hurtful to have to go through a friend breakup. IMHO, the day your friendship with the groom very viscerally ended (and for good reason as you said), with you actually telling him that you couldn't be friends with him anymore - you were done as a member of the wedding party. You should not stand up for this couple if you are actively refusing to be friends with the groom- and I understand it is his bad behavior but that's still the way that it is. My guess is the bride thought you and the groom would eventually come back around and when you didn't, she did not have the guts to say to you, "You cannot be a member of the wedding party anymore." I'm not saying what she did was right - but I am saying you should have realized the impossible position the bride was in once your friendship with the groom died. It wasn't about you so much as it was him, the groom.

I am very, very sorry that this is so hard for you. I'd recommend just texting the bride that you don't think you should be a part of the bridal party anymore but that you genuinely wish her well with the wedding.

As a final note - I really doubt, unless they are petty people - that the Facebook tagging about the shopping was just to rub it in your face. People tag happy life events, and dress shopping is one of them. It really is probably not about you. You are not even friends with the groom anymore - I think you need some distance and space to disconnect from this drama.