Should my friend tell my mum who I sleep with?

It should be your own business if you are an ADULT which I am hoping you are if you're sleeping with other people

How long had you been sleeping with them for? And to be honest, it's not their place to say anything about it, it's YOUR relationship, not theirs. They should have asked for consent to tell her first... Not that your Mum would like to know anyway, I wouldn't worry about it, is this the first time this has happened?

Okay then, just ask her not to tell your Mum again and it shouldn't matter too much, you're going to be fine with it, it'll all blow over in a couple of weeks.

If you expect your mother to financially support you (and perhaps the boyfriend and child), yes, it's her business. You and your boyfriend have been trying to get pregnant for some time (according to your other posts). Why would this surprise your mother?

As I recall, didn't you also have a miscarriage?