What you should do depends on what you want. If you want a relationship that is going to go somewhere, like marriage or monogamy and living together, I think you’re pretty clear that this guy isn’t going to give you that. Since you are in love with him, I don’t see how you can move on without breaking up. Making it a clean break will hurt a lot in the beginning, but will allow you to heal and move on a lot more easily than trying to date other people while you’re still seeing him and in love with him.
Most women have trouble being in love with more than one man. So if you want a monogamous relationship your best bet is to break up and move on. You’ll have a better shot at true love if you’re truly available.