sending lots of hugs you sound so brave talking to m. taking control, you are in complete control over your relationship with her and that is amazing considering how difficult things clearly are for you. well done.
as for the op its self, i can completely understand your worry, i have been under twice, once when i ws a kid to have molre removed and dont really rememebr,the other when i was 21 to have all 4 wisdom teeth out which i was really scared of. they get you to coumt backwaards until you fall asleep, usually takes a couple of numbers, but the nurse was very kind and held my hand , i reckon letting them know of your anxiety they will be supportive. i do remember when i woke up i freaked out because io had a mask on my face and was a little disorientated, so maybe ask ihow it will be when you come about?
do you have anyone that can support you at this tough time?
Is there a relationship between self harm & internet forums? Can you help answer: research questionnaire Jan 2018