OK, so i take it your mum is unaware of the situation. I havent told my mother either as she simply wouldnt understand, especially the ADs it would freak her out. So i sympathise.
But dont worry, you have done the shitty bit so you are going to be less likely to break down on friday anyway, well not to the extent that you will have panda eyes. Tell her its a routine gynae/smear appointment and its a double so likely to take longer, then you can fall back on the whole, i was waiting for ages scenario - take yourself off for a coffee or a walk, wash your face and get yourself together.
You'll be fine, the doctor has told you what is going to happen, so nothing new is going to be suggested on friday, they are simply making sure you are OK in the meantime. It will be a good opportunity to have a rational chat with the doc about what will happen, you can ask some of the questions you have asked here and be in a better frame of mind to listen to the answers. I honestly have found it so much easier to be objective with my doctor since the initial breakdown. In fact i find it easier to go and see her following a bad patch and say, look, ive had a bad couple of days, what shall we do now? sort of thing.
I seem to have verbal diarreoah of the fingers tonight. Im going to go to bed i think.
Dont worry about your mum, she might get an inkling something is up, but she wont ask i promise. Talk to her by all means if you think you can, if not. Fall back on, bloody uncomfortable smear test and the nurse with ice cold fingers!