Dear Flahers, Rudiraven is so right in that you have nothing to feel guilty about. You have your own life to live. You and your immediate family are the most important thing right now. Your mam chose her own life to live and she has to live with the repercussions of her own actions, and that includes how she has alienated and literally psychologically abused you. I don't know what types of aid or support groups are available in Ireland for your mam, but are there any groups that offer help with elderly needs? You say she is very fit, so maybe she doesn't need any real help, in which case, you can get on with your life as Rudiraven suggests. Just knowing you have done the best you could in your life should be satisfaction enough for you to move on with peace of mind.
Good luck and hugs,
Misty125