I lost most of my response. I really don't learn!
Uh, your mother's husband sounds really creepy. I hate stuff like that - is he just really immature for his age or is there more to it? It's so hard to tell with some people. Refusing to give you your purse is pretty screwed up, as is dragging you around physically without telling you why. I wouldn't be in any hurry to visit, either, hotel or no hotel. I think of hotel + my own vehicle as sanctuary and escape route. Just knowing that I am not trapped, that I can choose to leave any time I want, is really a big deal. Part of the reason I hate visiting the in-laws is because we are staying at their house in the middle of nowhere and we take a vehicle I can't drive.
If you can, I highly recommend adding screaming or increasing the volume to your freezing. I have found that making a scene and being very loud in those situations can be effective. Whining may make them hold onto your purse tighter - having everyone staring at them in a public place, even if they think you are the one in the wrong, makes them let go. I believe it is a good deterrent also.
My mother has still not mentioned the event, yay! She throws a fit if we skip Mother's Day gifts and celebrations, and it's just not worth it. I do the bare minimum to make it look like I did something. I am sort of tired of doing all the work for my brothers, so I told them they were on their own this year. I did breakfast and got it out of the way, they could figure out the rest of the day.
Oh, photos! I don't let people take mine either. However, I also forget what people (and pets!) look like! I've done the same thing your mother did, ask someone for a photo so I would remember them and have them get upset at the idea that I would forget

I have trouble visualizing.
Re: high strung - do you find that it is getting worse as you get older? It is for me. Things that I used to be able to do easily, I now am very resistant to. I also try to remind myself that most of the stuff I get worked up about is not really that important in the scheme of things - and my new favorite idea is that reality is not going to change, no matter how I feel about it.
re: selling ourselves without experience: no one has enough experience. Some people can accept that more easily than others. I am the same way, never good enough to do whatever it is I want to do, always waiting until I learn X or do Y first... but look at the people who *are* doing these things you want to do. How often do you think that they are competent? Assuming you are like me, you look at those people and also think that they do not have enough experience be doing X, but that doesn't stop them from doing it.
Did you get a response from your boss about that meeting? The video port guy has been a thorn in my side lately. He doesn't have enough work to do so he just invents stuff to complain about.