Just because you don't fight in front of your children doesn't mean they don't see, hear, and feel the tension in the house. Please trust me on this. I know so many people that didn't get divorced when they should hvae for one reason or another, and it hurts the children either way. The question is, do you draw the pain out over time, or do you get it over with and move on with life?
Seeing a therapist is a great idea. Perhaps you should even consider a marriage counselor. Before you object, hear me out. Marriage counselors can help kindly end marriages just as well as they can save them. And, who knows. He might even come around and stop being an asshole.
Now, please understand that we say the things we do here because we do actually care what happens to folk. We're not here to make you feel better about yourself if you're not doing the right things. We just don't go in for that. The people here have gone through a lot in their lives in many cases. Indi's old-school married. I've been the cheating asshole husband.
But about your kids, yeah, you're hurting them. And it sucks. You're obviously trying not to, but they're hurting and they know what's going on. Kids are weirdly observant that way.
Good luck finding your way to whatever happiness you can, make sure that if you do divorce that you take the time and put in the effort to heal yourself before engaging in any serious relationships.
"Well, then," the Cat went on, "you see a dog growls when it's angry, and wags its tail when it's pleased. Now I growl when I'm pleased, and wag my tail when I'm angry. Therefore I'm mad."