Ok well, that changes stuff up a bit. Yes there are people who have online Doms or subs to satisfy the D/s need in their life and have a vanilla partner irl and among these people, there are those who choose to have their vanilla partner in-the-know and those that keep it a secret.
I believe the general consensus is that it is unethical not to have your vanilla partner know that you have a D/s relationship with someone else (online or not, physical or mental) as a lot of people consider this an affair.
I don't know your situation with your spouse... like whether you are happy in your marriage or you feel like you've lost site of why you got together in the first place, if you are staying because of responsibilities to your children or if you went looking for a D/s relationship because you didn't want to talk to your spouse about D/s.
If it's just the D/s that seems to be missing from your spouse, I'd suggest talking to him about it and introducing the idea and starting with some light stuff you might want to try like blindfolds or something.
If it's not just the D/s then I really don't know what to tell you.