Should I stay or should I go?

Im 26 and been in the same relationship for 10 yrs. He is the only person Ive ever slept with and we have a 5 yr old with mild autism. Im not happy in the relationship anymore,I do love him and he takes good care of his family,but im not IN love anymore. I have talked to him about it and he dont want me to leave,so we talked about having an open relationship...I feel very selfish..what should I do....