Can I still make amends with my boyfriend's mom?

My boyfriend's mom has held grudges against me over the last couple years for things that my boyfriend has forgiven me for long ago. My boyfriend and I have kept our distance lately from her, but I was encouraging him to try and make things right between us. He did his part and talked to her over lunch one day. But he told me she was still hesitant and wanted to just invite him over for the weekend. Anyways, I was hurt that our attempts to make things work were only punched by her continued judgment of me. I sent a nasty letter telling her I'm tired of her trying to break him up with me and her negative comments towards me. I told her my boyfriend fears commitment, because she's been in and out of so many relationships, she's getting married for the third time. The last time he told her he wanted to propose to me, she convinced him to walk out on me. I went on about all the reasons I don't feel comfortable with her. My boyfriend freaked out and is feeling forced to move out (we've been living together almost 2 years). He says he loves me so much but doesn't see any way for us to work unless his mom finds it in her to forgive me. I stupidly sent 3 apology emails, pouring myself out and admitting all my jealousy and insecurity about why I said what I said. But the fact is, I don't like her family, I just want to have a working relationship with her. Her fiance and brother harrassed me with terrible emails after I sent her the first mean email. They went overboard though and called me names. I never called her names, only expressed myself. I don't want to lose my boyfriend over standing up for myself. Is there anything I can do to smooth things out? I admitted to her that everything rests in her hands at this point. She knows my boyfriend and I love each other and want to get married. She knows she has the power to break us apart forever. What can I do? Should I buy her something or show up at her place? Besides admitting to her that she was right and I'm wrong, and promising to never speak to her like that, what else can I do?