Name changed but regular.
I've been volunteering at an major public sector organisation for 5 years (totally separate from my career), when I started I quickly became best friends with my supervisor 'Mark'. Mark is one of those ultra charismatic types who goes out of his way to befriend everyone, mr popularity, but he treated me as special and yes it was a thrill. Nothing physical ever happened between us (I'm gay) but basically it was like a relationship. We regularly went on dates to the cinema, theatre, dinner in nice restaurants. He fixed broken appliances in my home but I genuinely thought we had a beautiful close friendship. I stopped by his office to hang out all the time. Texted constantly. Referred to each other as husband and wife. Went on crazy adventures. I knew he sort of had feelings for me. For example he's of a minority race and religion and he asked a lot of questions about my parents' expectations for my marriage, was I expected to marry someone of my race/religion, how would they feel about me marrying someone of his race/religion. He got very upset when I said I didn't want kids. He often told me how beautiful I was. But at the same time he'd made a big deal of saying he saw me like a sister or that for him I didn't exist below the neck.
I don't want to go into a whole psychological thing but I was badly abused as a child and have a lot of mental health issues, and struggle with poor boundaries. I spent years very badly socially isolated. Mark was really my first friend. I'm not disavowing responsibility because obviously I should have realised having such a close relationship with my supervisor was a potential conflict of interest issue, but to explain why I sort of 'fell' for him and why the friendship meant so much.
Last year Mark met an acquaintance of mine, and they started dating, fell in love, and got engaged after a few months. The minute they got together he stopped speaking to me completely. It's nothing to do with the woman who is absolutely lovely and had no issue with our friendship at all. It really hurt, and made me reconsider things from the past. For example he used to tell me all kinds of private and negative things about the other supervisors and other volunteers, and he used to tell me they hated me, so I quickly ended up basically alone in the programme except for him. He was controlling in other ways and got a kick out of using "social engineering techniques" to control people. I've also found out that what I considered his informality was actually special treatment that only I and a few others got. He let me choose my own schedule and what I wanted to do. He handled any issues himself without reporting them. For example one of his co-workers he was good friends with grabbed me and tried to aggressively play-wrestle me in front of visitors, and I slapped him. Mark dealt with it and swept it under the rug without any official report being made (this is a place where you have to fill in a form if someone grazes their finger).
I've stopped volunteering but I really want to re-start as it was a major part of my life and I miss it. I'm not sure how to handle things. I don't want to be around him at all but I don't want to complain because it'll turn into a huge formal thing (he definitely committed fireable offenses). I'm okay with only volunteering on his days off but I don't know how to tell them that without it turning into a drama. Also they use a single email address so anything I send to them, he will read.
Am I right to feel aggrieved, or am I just hurt at being dumped? Is it my fault? Should I say something to them? Should I go back and ignore him? Or just leave?