How to avoid someone (in the family) who is a trigger?

This is one of my first posts so I'm a little nervous. I would like to see if anyone has any helpful input or have had a similar experience.

I have lived on my own for a few years. I moved out because my stepfather was very emotionally abusive to me, very mean and controlling, even went as far as putting a lock on the fridge so I couldn't eat, and invading my privacy big time installed a program on his computer so he could spy on everything I did online, my chat conversations with friends, what websites I went on, and would either get angry with me about it or use that information to make fun of me and taunt me (this even went on even when I was about 20). Would call me a ***** and gross. It goes on. On top of that, he has been doing something illegal (would rather not say what), nothing very serious or harmful to others, but still wrong. He has worked very little in the past 13 or so years, hasn't held a full-time job, not for any legitimately acceptable reason, just out of laziness. So that means my mother pretty much supports him.

No one did any thing until my grandfather found out about what was going on and encouraged me to move out at about 20 years old. He also threatened that if my stepfather didn't stay away from me, he would take legal action and turn him in.

I have barely seen him since, only twice, and both times I was very upset afterwards. Both times were when I was feeling very depressed and it triggered really bad thoughts, especially made suicidal thoughts worse. I've been diagnosed with bipolar so I need to be careful of mood swings. Being around him, I know for sure would trigger a bad mood. It's not just about how much he's hurt me, he is an all around negative person to be around. Being around him is simply not an option. My life is SO much better without him. That would be like a recovering alcoholic walking into a bar..

It's hard though because he is always invited to family functions, like BBQs and Christmas (even though no one else likes him), so I can't go because I can't stand to be around him. It's been hard to decline invitations.

This has put a lot of strain on my relationship with my mother. She acts like she doesn't understand and claims he is such a good person so I should be around him. The only time I can see my mother is if I go out to coffee with her or invite her over to my place, but she doesn't like making the effort and prefers me to go her. We haven't been very close in a while, because of this, but also because she has done some things that have hurt me(for one, stealing money from me) so I've lost a lot of trust in her. It's always a push-and-pull kind of relationship with her. I really want to forgive her and try to get closer to her and sometimes she allows it but other times she pushes me away and makes me feel guilty for moving out and not being around my stepfather. At one point she told me she "had too much stress in her life" to see me, so I didn't see her for months, which was really upsetting- how can a mother say that, and not make time to see her daughter? I really long to have a closer relationship with my mother, I really miss her, but it's so hard. I have also pulled away from her at times and told her I don't want to see her for a while if she has done something hurtful. But I really really want to fix things with her.

The major problem right now she just got back in touch with me and just moved into a new house and keeps telling me how she wants to take me to see it. But that would involve being around my stepfather, since he obviously lives there. It's in a rural area outside the city and I don't drive so she would need to pick me up. Her last house burned down in an awful fire she lost everything and it was devastating. Everyone survived but they lost the whole house and everything inside. At the time, I was living with relatives at the other side of the country, and those relatives were concerned for me, and very protective, overprotective- they were afraid of her hurting me again and didn't want me to be supportive towards her. Didn't want me to talk to her at all. Said if I talked to her they would kick me out.

I've moved back to my hometown several months ago and really want to support her but don't know how. How do I see her now that she lives further away? I guess the only solution would be to invite her over here to my apartment. I just don't know how to explain to her that I won't be going to her new house. Every time I try to explain why I can't be around my stepfather, she ends up fighting with me and guilt-tripping me. I really don't know how to be supportive of her but I feel so guilty for not supporting her back when the fire happened, instead I let my relatives control me.

I guess I'm just looking for suggestions for what to say because I know I will need to decline going to her new house and I know she will be angry. And no matter what, I will feel so guilty for not supporting her during this difficult time.

What would you say? I'm overcome with anxiety and guilt.

I'm an artist so I 've been making some art and other decor items for her new home, but how else can I support her? And how else can I rebuild my relationship with her?