Re: brother
You are correct. This is the only chance you have to make things right for the man who did so much for you and your family. If you truly feel guilty for your selfish actions and want to make things right and live your life guilt free, then support your brother’s choice. Stand 100% behind his decision to marry this woman because she makes him happy. For once, support your brother and allow him to do something that makes HIM happy and don’t interfere. Not only should you let him marry his chosen woman but you should actually help him plan the wedding and help convince your mom that this is the best decision for him.
This!
You realize he has worked so hard for each of you, you should stop treating him like an ATM machine. Let your mom deal with how she wants, but at least you can be there for him now.