Sorry for me coming late to this post. Since you have a problem with your mom taking money from you, maybe she needs some financial advice. If she works and collect funds from your dad - she should have enough money since you live in a trailer with low expenses(assuming). Since you're an adult, you should be giving her some money but not beyond that.

I know your abusive history growing up and I suspect your mom may be codependent as you recognize...so you need to set boundaries. Since you're thinking of taking training to get a job, hopefully you'll be able to afford your own place. In the employment agency - they may have placement and training for women/men over 50. Your mom needs to stick with a job, even if its not perfect - you can't be her safety net. I feel you're a good son but you need limits.

I agree your mom probably has mental health challenges from your dad's suicide and even before that...with her tolerating your dad abusing you. A normal women wouldn't let her son be abused. I agree with the others you're smart and deserve a good independent life.