"If we divorce, he doesn't think I am entitled to any part of the house since it was acquired before we were married and he is the only one on title."
He's wrong, but he's in a better position than if you had acquired the house after the marriage. The house is his separate property because it was acquired in his name before the marriage. However, if you were to divorce, you would be entitled to some interest based on the contribution of community property funds to the mortgage payment and any post-marriage improvements (I can't tell from your post whether the existing house was built before or after the marriage).
"I think it counts as community property(we live in CA) since our money has been co-mingled since we were married and when I worked (before we had children), my money helped to pay the mortgage, etc."
Absent a prenuptial agreement, their is no "your money" and "his money." While his paycheck might be made payable only to him, both spouses' earnings during the marriage are generally considered community property.
If you're contemplating divorce, consult with a local attorney.