I need advice coming to terms with this situation, AIBU and is NC the best/only option?
Throughout my life, my DM has suffered with severe depression and with that has come a number of issues. Without explaining everything in detail - she has always prioritised her own emotions and the emotions of her various 'partners' over her children. She has always thought that she needs to be in a relationship and with that came a long string of unhealthy, toxic relationships. All of which were pushed upon myself and my siblings throughout our childhood. 'He's part of your family' etc.
Recently, she has cause a huge scene about coming to my graduation because she can't bring her current boyfriend. I never thought I would be able to accomplish a degree due to my difficult childhood and having to financially support myself from 16 years old. I could only get a maximum of 3 tickets, and she knew that only my close family would be invited, but gradually got more and more argumentative, saying that I was deliberately trying to exclude her boyfriend and am disrespectful towards her 'long-term' relationship 
Now she has refused to come after I'd paid for her ticket because her boyfriend 'has anxiety issues and can't be alone'. This is not the first time this has happened to me, and she has also refused to come to my sisters wedding two days after for the same reason. She originally said she was bringing him to the wedding anyway despite him not being invited, then decided she's not coming at all.
We are all at disbelief that after everything she has put us through, she can't put her feelings aside and celebrate her own children's accomplishments and events.
AIBU!? Or should I just accept that it's an unfortunate situation and carry on building my life without support from my mother?