Idk what to do

So my boyfriend we been dating for 4 years just recently these past months he's been dumping me off and on . Cuz he dont know if he loves . Yet when we alone or when he with me he tells me he loves me and want me but when I'm not with him he says he don't want me . Yesterday night he texted me drunk and told me he is in love with my sister . And he showed me pics of her on his phone that he screenshots . Idk if he is lying or not . Im scared to leave him , because these past years it has been horrible for me the only way I found happiness was with him and now he acting this way . He says he loves me one day and the-next he don't . Like I'm such a great girl Ik Iam . I give him sex and love and respect him . He used to hit me and I forgived him . But now idk