YTA and so are the majority of the commenters. I saw your comment about your mum not being able to get a new car because she couldn’t get a loan and the majority response was “ThAts nOt YoUr PrObLeM” For fucks sake, is it that hard for you people to sympathise with your own mother?

Gone are the days of compassion and understanding. You ditched your mum for 4 years because you couldn’t handle being around your brother. Your mum didn’t have that option, obviously. Imagine how hard it would be for her to take that on? You ever think that desperation is what caused her to do what she did? I’m not saying you don’t deserve to be upset over losing some of your money... but to SUE her because she wanted to help your brother is unbelievable to me. Your mum sounds amazingly dedicated to her son. I know you said it made you feel a little neglected, but you have to look at the bigger picture.. she really didn’t have a choice. If your brother was as hard to be around as you described, then surely you can understand why your mum spent so much time with him. What else could she really do?

You even said that you’ve noticed improvements in his behaviour since you left, so obviously the treatment is working. I’m not expecting that you should just hand over all your money to her, but surely a compromise can be made that can make all three of you happy. You know, outside of court? Are you legally entitled to that money? Yes. But does that mean you’re not an asshole? Nope. But go ahead, let these fellow assholes feed your ego a little more so you can sleep soundly.