'Best friend'

I had a falling out with my best friend a few weeks ago. We were both under a lot of stress and she didn't agree with some of the choices I made. She had been helping me (and my husband) out a lot and I think she felt as if I ignored her advice. That wasn't the case. It was just that I needed to make my own decision even if it was going to be the wrong one. Our relationship became quite strained after that and she completely stopped talking to my husband because I disclosed something he had said about her partner. My husband and I were on a break at the time and when we got back together, he was pissed that I'd broken his confidence. He told me that it was my fault my friend wasn't talking to me as much because of what I'd said, that her fiance didn't like me any more (I have been friends with him for even longer than her - and it was me who introduced them) and he told me that I could never be her friend unless he patched things up with her. So I tried to smooth things over with her by saying that I may have got the wrong end of the stick about what was said and exaggerated it. That wasn't the truth by the way, but I wanted everyone to be talking again. Since then she stopped talking to me altogether.
My other close friend who works with me and her kept telling me to give it time, to keep telling her how much she means to me and not to give up. Every text or Facebook message I sent her was ignored. I was passing through work yesterday morning and stopped off to say hi to my friend and not-talking-to-me friend saw me. I smiled and she turned her back on me - three times. Then my train came and I went home. I told my other friend what had happened and again he told me to give it time. He said that she was so upset that we weren't talking that she'd been crying to him. I sent her a text, but she didn't respond again. I planned to go and see her face-to-face to sort things out.
Then this morning a letter came to me and my husband (we're on another break by the way). It was from my friend and her fiance saying that over the past couple of months our relationship has been destroyed beyond repair, that one or both of us had told them lies, that he and she were there for us when we were having problems and it was obviously not appreciated. They said they're grateful for me getting them together, but it would be pointless to carry on the relationship and that we are uninvited from the wedding in two weeks time.
I'm completely devastated that this has happened. I feel like history is repeating itself all over again. They're two more people to add to the long list of relationships I've fucked up. I love them both so much and I always believed it when they said we'd always be friends. I may have seemed like I didn't appreciate their help but that really wasn't the case. I was just in such a bad place. My marriage was breaking down, my work situation was about to change and I was just starting my ED treatment and my grandmother died. I never meant to take advantage of anyone. But it seems like that's what I always do and that's why everyone ends up hating me. I feel so hurt that she couldn't come to me and tell me what was on her mind or even tell me that we officially weren't talking. It hurts that I'll never see her or her fiance or her kids again and that we'll never be part of each other's lives. How can you say to someone that they're your best friend, that they're like a sister to you and that you'll always be there for each other if that's not true? What's wrong with me that I can't see what I'm doing to people or how I'm pushing them away or treating them badly? I don't mean to hurt people, but it seems like no matter what I do I always end up hurting someone and always end up being hurt myself.
Why would she have said that only yesterday if she's already posted the bloody letter and blocked me on Facebook? I'm so scared now to talk to anyone or trust anyone because I don't want to drive away the few friends I have left