What a situation.
How old are you and your brother? Are there other relatives or friends who can help? Even going away for a few days and getting a break can be very helpful.
Always keep in mind that this is not normal, and that it’s not a curse you are bound to repeat, you and your brother will no doubt be wonderful spouses and parents and this experience will make you even more sensitive, although, I realize, it will be a scar that does not go away. Your mother must be suffering a lot, try to have compassion if you can, may we never be in her shoes.