I'm sorry for what you're going through

I think you should talk to your husband about this, you two really should have a long and honest talk. People often stay together because they think it's better for the kids. In my experience it's a huge mistake whose consequences are often worse than those of a divorce.
As Berries said it gives the kids the wrong idea about what marriage and family are supposed to be. But what is even worse is that they'll have to watch the unhappiness of their parents every single day and they won't be able to do anything about it. Staying together for kids' sake is going to be much tougher on them in the long run then the stress of a separation.

I wish you luck