I'm 15 and haven't had my period for about a month - I really don't want to be pregnant

Ok, I'm 15 years old and I recently split up with my boyfriend (well not that recently).

Anyways we were mucking about as normal couples do and he sorta started masturbating and ended up fingering me. Now I'm not sure but I think some of his sperm got onto his hands and went into me while he was masturbating.

Anyways then I dumped him cos I had heard he was cheating on me so I dump him and about 5-7 weeks after I dumped him I get serious stomach cramps and am thinking 'what's happened?'

I didn't take a test yet cos I didn't know if I'm pregnant and if I am I don't know how to tell my parents. My dad said that if I ever get pregnant b4 18 he'll kick me out and said I can live with the father, but I hate the father now and wouldn't live with him. Anyways he's going out with my mate so it would be kinda awkward.

My friends keep telling me to do a test but I can't cos I don't wanna see the verdict. If I am I'm in a lot of trouble and I can't get into trouble as I'm in enough trouble as it is.

PLEASE HELP I DON'T KNOW WHAT TO DO and I haven't had my period for about a month or so now but I really don't wanna be pregnant.