IDK what 2 do?

i was talking 2 my bf on the phone and he asked me,"would u be mad if i had with another girl." im like no id be happy.(jk, jk). well he asked me because he almost did. i asked him if he would ever cheat on me and he said no. i also made him sware on my moms grave(she died). he still said that he wouldnt. his dad is friends with my friends mom, and she said that i should belive him because his family is not lke that. oh yay i am only 12 and he is only 13. he says he loves me and he know that i am in love with him. i just wanna know what 2 do? can u help me?