I am so, so sorry that your mom abused you and that now you're in this position.

Honestly, I think you'd be 100% justified, when she dies and people start bothering you about it, in lying through your teeth and saying that the two of you had a tearful reconciliation straight out of a Hallmark movie, or that you tried to contact her to talk things through but it was too late, or something like that. People who would punish you for keeping yourself safe from abuse do not deserve the truth.