I am sorry you have to go through this , unfortunately even parent's have their problems, it sounds like your mum is suffering from severe depression, i guess that is what the meds are for, maybe her meds are not the right ones for her, just know its not your fault any of it, and you are not making her feel a bad person, she will probably be feeling this way no matter what you said, it will all be part of the problem.

I don't know what has happened to your parents marriage, and whether there is hope for a reconcilation, it sounds like your dad wants that, only time will tell I guess, but in the meantime, try to think positive, i know it is hard on you, and hope for the best outcome, it just may take time for your mother to get well.

HUGS TO YOU.