I've been in a relationship with this person for 4 years and I'm not invested in our relationship anymore. I've told him this numerous times but he cries to me and refuses to leave the flat we share and it makes me feel like a terrible person.

I fell out of love with him in September 2016 the last time we went abroad as he is an awful drunk and I've been sleeping with someone from my work as well (just to complicate things even more).

I really need advice on this it's really getting me down how do I get the strength to seriously leave him?