Met up with a guy online and have mixed feeling about what happened

So I was feeling horny one night and decided it was time to finally get a BJ. I am a anal and BJ virgin mind you so this concept of getting naked with someone turned me on. I went, found someone who would help me "learn the ropes", and we met.He was older than me for sure. Me (19) and he (30's) but that did not bother me. He blew me and I blew him. It was pretty fun, I wrapped my legs around him and he would rub my legs. But after we were done and I was driving home I felt kinda mixed. Like, unsure if that was fun or me being slutty. I also felt extreme guilt since my parents have no idea, my friends have no idea, no one has any idea of what just happened. Everyone I know thinks I'm straight not Bi.So I guess this is where I ask for your opinion. Was this a bad thing to do? I think it's normal to have a sex drive but I just feel weird about the entire thing. Was he lying about being clean? The worst part is I might go back. It's just...I don't know. I need some help in deciding what this was. I have no illusions about the emotional side here. It was just sex, thats it. It was fun but not fun. You feel me?