What to do ? I'm confused . ?

See , when I was four , my Mom married my stepdad . & I asked him to be my Dad , because Mama kept me away from my biological father , because he always tried to make her stop popping . Well , my stepdad makes me kiss him on the lips , sit on his lap , when I get up , he'll pull me by my belt buckle back to his lap . When we cut up , he'll slap my butt , but grab it at the same time . & is always giving me titty twisters or thumping them . & he makes me lay down with him , when he does , he lays on his side & makes me lay on my side in front of him & he puts his arm around me . & when he makes me kiss him , it's like six or seven pecks on the lips at once . It all makes me feel so uncomfortable . I regret asking him to be my dad . & my boyfriend is already holding back from fighting out of respect for my baby brother & sister . & he only treats me like that . Not his real kids . I don't know what to do .. ..