My boyfriend cant get over my past and he wants to sleep with someone else ! whats the right answer ?

i have been with my boyfriend for 15 month now and he was a virgin wen i met him and i him and i had slet with someone he new, he tried to ignore it for months but he cant and now he thinks it will mak our relationship better if he went and slept with someone else !! he says wen i moan at him it just pushes him to go out and do it more, he wants to go out and have fun basically he said he wont come near me or kiss or touch me or even have sex with me... i dont want to loose him but he is calling me names like sl*g and stuff and tht i will open my legs for anyone because of what i done i cant finish with him because i love him so much but i cnt stand the fact that he is going to sleep with someone else !! i know ive done wrong by moaning but its my insercurity and worry !! but am i stupid for letting him go out and sleep with someone else.. he says he loves me but if he did surley he would not go sleep with someone else !! but i quess he cant help it if he cant get over my past !! helpp my head is so mashed and its tearing me up inside im 17 years old and never thoguth i would be in a relationship like this things were brilliant at first but he just blew one day i still love him like a did day 1 and i always will but will it make things better if he sleeps with someone elsee ?? i hope someone can give me right answer pleaassee x