Am i being taken advantage of?

I just turned 20 last month for the past week I've been living with a guy I met and started dating a week ago. He's 22 and a prison guard. Last night while he was away I got drunk on Mikes Margaritas that were at his house. It's the first time i've ever been drunk and when he got home we had sex. I wanted it and all but after talking to my ex-fiance of 4 year's best friend today and telling her....she said that any sober guy who has sex with a girl who has never been drunk before and is underage is taking advantage of her. She also said living with a guy for a week and him saying he wants to have the next 70 years with me is downright crazy and he's using me. It really pisses me off and I think she's just trying to tell me how to run my life. Opinions?