Oh, dear! Be prepared for her not to take that well.
My mum wasn't at the birth and will forever hold it against me. She is also a very 'me' person, to the point where myself and a psychologist friend of mine believe she has a personality disorder, and everything is about her and how it affects her. I think she has realised since mid-pg that the birth was going to mark my breaking free of her 'grip' on me. She is still not dealing with it well and things come out all the time that I can directly link to her not being able to control me and guilt me into pandering to her emotions. Her emotions are not my responsibility, so long as I don't do anything with the intent of hurting her. She doens't get that, probably never will, and I had a fantastic birth, just the way I wanted it, without her there. Nothing will ever take away DS's almost perfect birth, not even the fact that she flipped and wouldn't see us for a week and a half afterwards.
You sound like you are a strong person, and whilst it might hurt should she also 'flip' the way my mum did, you will prioritise your own family and not bother with walking on her eggshells after the birth My mum hates that I don't care about her emotional booby traps, her eggshells, her baits...hates it. It will be a long time before she accepts that!
Enough about me (!!), you are not alone with the difficult mother saga. What the others have said is true - the most important thing (despite what your mother might have you believe) is you, your baby and your DH. This is the one time that it is most definitely about YOU and whatever you feel comfortable with. The hard part is to shut out the guilt, but you WILL do it when push comes to shove (pardon the pun!), so and best wishes!