Should I or shouldn't I? Help!!

My mother was/is involved with a man who added me on fb and called me and mother whores-he doesn't know me never met me or anything of the sought and how could he say something like that when he was or is with my mother? That was the first impression that i got of the man she was with or is with i don't know because she would not tell me.i used obscene language at the man involved with my mother.i told my mother what happened she agreed with what i did but somehow she tried to cover up what he did by saying he was just joking ... i don't know if she is or was in an abusive relationship with the man...she wouldn't tell me that and i hope that wasn't/isn't the case. When i told my fiance that he was mad at the man but then he was mad at my mom too for trying to cover up her man's wrong doing.i understood but i also wondered about her relationship with the man and hoped she wasn't being physically hurt.Anyway,when (A)-my fiance- heard of me going away in the US...he wondered about my safety and tried to reasoned with me all possible dangers of human trafficking and wondered if my mother would hide my passport so that i could not return to the caribbean,he wondered if i would be living with my mother by herself or with my mother and her man-which is reasonable...Also,he feared that i might not want to return the same way his ex didn't but i told him that i wasn't his ex that i wouldn't do that, that i just wanted to see my mother and spend time with her and my family over there...i haven't seen my mother for eight years now and my grandmother for 14 years and i don't want to be the one to pass up the opportunity of doing that before it's too late in case my mother or grandmother passes and i never got the chance to say or even hi after all these years but i feel bond because i'm engaged with (A) and i don't want to leave him because when i leave i would have to stay in the US for some months,i love him.i'm caught in the middle of not knowing what path to choose! It's torture!i miss the bond that i haven't had with my mother for so many years as well as talking to her in person and meeting my family from her side but i am in love with (A) and don't want him to feel that i'm leaving for good.