I think the first step is to have a long, serious, clear, blatantly straightforward conversation with him. All these things you just told us? You need to tell him. Once he knows how important BDSM is to you (and it sounds as if it's very important to you), then you two can both approach whether to stay together or not. But being in a sexual relationship with a person who has different sexual tastes from you can be difficult (and that applies to all different kinds of tastes, not just BDSM). Some people can give it up and still be happy; others cannot. Unfortunately in the end, no one can decide that but you.

My biggest suggestion: don't listen to what other people say about whether you should stay together. Follow your own heart and mind: you know best whether you're happy.