I don't know what the consequences of his sedative dependency are for you're relationship so I can't save dump him or stay with him. It's up to you whether a person having this addiction is a deal-breaker or not. I mean if it's as simple as he has to take a sleeping pill every night or he can't sleep then I can't see how that could affect the relationship negatively but if he's taking like 30 Xanax a day or something I can see how that could be undesirable.