How very sad. RIP to your poor Mam, and condolences to you.
Twelve years is a long time to be holding on to something as tragic as this. Do you think perhaps, your Mam might prefer you to get on and make a happier life for yourself. Would that be a better tribute to her memory? Rather than have the man you hold responsible as the centre of your life, for God knows how long?
If you have children of your own, what would you want for them?
I hope you find peace.