My mother can't get over I have had sex?

[Peggy]

I am 25 years old. Between graduate school and finding a job I was at home and my mother read through my Facebook conversations (private) with my friends while I was away. She found out I have had sex with people who are not my boyfriend. She knows I like to party (not to an extent, but I do spend Friday nights at the bars with my friends). She can not get over this and has told me I need to see a therapist repeatedly. She has called me a whore. I am happy with who I am. When I refuse her advice (this has gone on since she found out I lost my virginity to a long term boyfriend when I was 18) her go phrase I've heard many times is "go get drunk and f***)" I am a grown woman and this has torn apart our relationship. I have told her I am happy with who I am and she insists on trying to make me believe if I don't have her morals I am not a good person. It has gone on so long and I don't know what to do anymore.