He’s stuck in my life forever

How to get unemotionally attached to your best friends brother? Me and him dated for two months the end of 2018 dated for two months, He’s been in and out of my life each time he’s been in a relationship because he comes to me with his problems or at least to vent because he I’m one of the very few people he trusts, he deals with depression and I was always scared for him to be suicidal like he once was the last 3 girls after me were toxic and the relationships ended , before those relationship he would tell me that I fit every box but idk what happened, I’m super close to his family and his sister is my best friend so I’m always at her house at least once a week , he doesn’t live with her but he’s there at the gatherings they have, me and him are currently friends with benefits and we don’t see each other just for sex , he is a good friend of mine and he go out to eat at least 1-2 times a week, obviously he only wants sex and someone to hold him and obviously I’m only doing it because I love him and have wanted to be with him because I know what he can offer to someone, I’m just stuck with him for life and it sucks because he’s unemotionally available and keeps telling me he doesn’t want anyone or a relationship with me despite him knowing how good I am to him, I know he doesn’t love me the way I love him , I want help with this situation because even if I stop being fwb, he’s still in my life