There are two different issues here: Your return to the Church and the religious upbringing of your children.
You have the moral right and duty to return to the Catholic Church if you have been brought to the realization that the Church was founded by Christ and that re-joining the Church is a matter of more closely following Christ himself. Such an action would only “split up” your family if your husband will not yield enough to concede your moral freedom as a fully-grown adult to do what you believe is right. In that case, the responsibility for such a “split” in your family would be his.
But you must accept that your choice to leave the Church and marry a Protestant has consequences that cannot be wiped away merely by your repentance, however good and sincere that repentance may be. Your husband married you believing that you were a committed Protestant willing to raise any children you might have as Protestants. Although your report of his attitude makes him appear to be harsh and unyielding, you must respect the fact that he too must follow his conscience in the religious upbringing of his children.
To him I recommend that he do his best to recognize your need to follow your conscience by returning to the Church you believe to be Christ’s own and that he not interfere in your practice of your Catholic faith. To you I recommend that you accept that your own life choices are what caused the fact that you now have a Protestant husband who insists that your children be raised Protestant. It is now your responsibility to pray for your husband and children, offer up any sacrifices and sufferings you may have to endure for their conversion, and to make Catholicism attractive to them by being the best wife, mother, and Christian you can possibly become.
When Only One Converts by Lynn Nordhagen
Could You Ever Come Back to the Catholic Church? by Lorene Hanley Duquin
The Secret Diary of Elisabeth Leseur by Elisabeth Leseur