I have extreme anxiety about HIV?

I had unprotected vaginal and anal sex with a woman at a party I was at about 7 months ago. About three weeks ago I went to a youth group concert/lecture at a friend's church and they talked about HIV and how it is not just a "gay disease", it's possible for it to be spread from women to men. This freaked me out and I began experiencing extreme symptoms of anxiety...I wouldn't be able to sleep at night because I would be so worried I had HIV. I would stay up reading every single website that came up on Google search for symptoms of HIV. It was on my mind every single day for a good part of the day. I finally got the courage to go get tested and the test came out negative. Even though the test was negative and the tester said that I am out of the window period, I am still so anxious about HIV. I have been refraining from having any sexual experiences with my girlfriend, even safe sex with a condom. I know I am clean but I can just not get this out of my head. My family is very religious and if they knew I had these fears and that I had unprotected sex they would literally disown me. I need to know how to quit having these irrational fears because I cannot live my life like this. I don't know how to see a therapist without my parents finding out.