I don't know what to do please help!

My friend and I decided to move in together she's been my very close friend for a long time I feel like she's family the only thing is she has two kids and I'm fine with that I would like to help her out since she's a single mom but the issue is my sister just found out and my parents approved they say that it's wrong for me to move out especially since they did nothing wrong and I don't have to pay for anything they still do yes I know they shouldn't because I'm 28 but they do it because they want to, they also say that I shouldn't be moving out since I'm not married and I shouldn't be moving out because I'll become a whore/sluts and apparently my dad thinks he's a failure because I want to move out and screw up my life and my sister is making me choose between my family and my friend/my life. Oh and she's calling me selfish.

Please help and tell me what should I do what do you think I should do or say?