If you fully paid for the new house with the proceeds from the sale of your separate property home, then that would be considered a mutation of your separate property and, unless you put your husband's name on the property deed of the new house, it would be your separate property.
If you did not fully pay for the new house and you have a mortgage against it, the new house would be characterized as community property and you would have a reimbursement claim against the property for the amount of your separate money that was used. Depending on what other correspondence was exchanged between you and your husband, he might be able to claim the down payment as a gift from you.
If you fully paid for the new house with the proceeds from the sale of your separate property home, then that would be considered a mutation of your separate property and, unless you put your husband's name on the property deed of the new house, it would be your separate property.
If you did not fully pay for the new house and you have a mortgage against it, the new house would be characterized as community property and you would have a reimbursement claim against the property for the amount of your separate money that was used. Depending on what other correspondence was exchanged between you and your husband, he might be able to claim the down payment as a gift from you.