Thing is, though, there’s no way to really forgive the past until there’s something different in the present. It seems to me like Mouse is trying to move forward and have a respectful, adult relationship with this woman. And her mom is responding by trying to control the boundaries and content of their relationship. Her mom didn’t ask to be forgiven for mistakes - she took Mouse to task for ever having been angry in the first place. It’s alllll about mom – there’s nothing in mom’s description of the past that allows that Mouse is a genuine human being with a full range of emotions. Mouse is just a foil for mom.
Is that yet another term for condom, “fucking helmet”? Perhaps the ribbed variety as opposed to a plain “hat”? 
A few months back, my mother called me and started talking about something a friend of hers had said that another friend had done and… “Mom?” yaddayadda “MOOOOOM!” what? Don’t interrupt me! “Listen to me and I won’t have to interrupt. And look at the hour. At what time do I go to bed?” uh? OhmyGod, it’s half past eleven! “Right. You just got in from the street, you’re all excited, wonderful talking to you, but if you wake me up during the first sleep again, I want to hear that your parents are dying or your house just burnt down, all right?” sorry honey! ok if I call tomorrow? “yes” ok! love you! click
One of the things that drives Mom completely off the wall is when any of Dad’s siblings calls her and leaves a message calling her “parrandera”, something like “hey, you’re always out partying!” - oh I’m sorry for having a life, do you think I must sit on the phone 24/7 waiting for your phone calls? It ain’t hatching! Maybe your mom thinks your phone will hatch! Isn’t that how the Mouseling will be born? 
Yeah, mom sounds pretty much like she has a borderline personality disorder, among other things. The OP needs to establish clear, strong boundaries, and defend the hell out of them. The consequences of not doing that are not pretty.