In a South Carolina Divorce, while it is not absolutely necessary to file for a Temporary Order of Separation and Maintenance, most people do where there are children involved so as to at least have a court order as to child custody and child support.
This answer is for general advice. It is not legal advice and does not create an attorney client relationship. For legal advice you have to retain your own attorney.
That is only a question you can answer. However, there are definitely a number of considerations that you should be aware of regarding separating and given that children are involved, I would suggest that you at least discuss your options with a lawyer. At least then you will be better informed on your particular situation and decide how best to proceed, good luck.
If you want to obtain a divorce or a decree of seperate support and maintenance then you will need to file an action in family court (or wait for your husband to file). Nothing happens automatically just because you and your husband seperate. I recommend that you contact a lawyer for advice and to discuss your legal options.
This is general advice and not specific legal advice to your particular situation.