He's in love with someone else...

My bf assures me that he's head over heels for me. I honestly feel like he is too. I'm his first GF in the past 2 years cause he said he was purposefully waiting for someone special. His family loves me and always pick on us for being in love and say I'm all he talks about. They see a visible change in his happiness when he's with me and I often catch him just staring at me smiling....but he recently told me he loves me and loves someone else. His first love...she died in a car crash 4 years ago while they were still dating. I'm not sure what I should do because my bf passed away 5 years ago next month from cancer but I'm don't still love him. It was hard but I accepted it and let him go so I could really move on. He can't even say she's dead cause he says it sounds too real and irreversible so he says she passed. I love him but how am I supposed to be with someone when part of their heart still belongs to someone who's gone? I feel like he can never fully love me.