AITA for wanting to go somewhere else (LONG message, sorry)?

**Background**: I would like to provide a detailed bit of background to the situation, because it is really important for how things turned out like this, but the rules and post-size restrictions make that impossible, so I’ll try to be as brief as possible.

Mum passes away, dad moves in with a new woman, her oldest son needs some place to live because their house is now too small for all of them. A deal is made where he gets to live at my place in exchange for paying for half the bills and his own food, but once he actually moves in, I learn his income doesn’t even cover his half of the rent.

I offer a new deal where he takes care of the housekeeping while unemployed, and pays the expenses for a year after he finds some place to work. Until he is employed, he doesn’t have to pay for anything expect his own luxuries. I even pay the food expenses for both of us. He agrees and I let him live at my place.

The first two years are fine, nothing noteworthy happens other that me noticing he doesn’t really seem to do a lot of job hunting. However, job hunting is slow and done mostly from the computer these days, so I don’t give it much thought. Eventually, he lands himself an apprenticeship and although not employed, at least has a road to employment now.

Enter the pandemic. I lose my own employment and the guy loses the employment opportunity he was promised as part of the apprenticeship. We’re both without income now, but I still had a fair sum saved up, so we keep up the arrangement with me paying now in exchange for him paying later.

Another year passes and my savings are starting to run dry. Just in time, however, he manages to get a proper employment. Not only that, but one that actually pays really well, considering how freshly employed he is. More than enough to cover all our expenses and still leave him with almost a third of his salary to put into his savings. Things are looking up.

Three months later, he moves out and completely ghosts me. I lose my home, I lose my investments, I lose my car and I’m left with a debt of almost $30k as a result. With nowhere to go, I turn to my dad and am allowed to move into the heated shed they’ve got standing in their yard.

I’m treated fine, I guess, despite the son of the woman in the house being the cause of my suffering, and I mostly keep to myself. However, come this year, the son is apparently planning to come down for Christmas and I told my dad and the guy’s mum that if he comes down, I will go somewhere else for Christmas so as to not ruin the moment for anyone else.

To that, I was told to stop dwelling on the past. To forgive and move on. To stop "being an asshole". But I wanna go away because I don’t have the confidence I’ll be able to remain calm and civil if I see him and I don’t wanna cause an issue for my dad (he’s kinda old), regardless of how and what my personal feeling and opinions are on the matter.

Am I really being an asshole about this?