You should talk to an attorney asap, but some things to consider:
anything you inherit is generally non-marital, but you can comingle that money and then it may become marital, the debt that you are accruing now will be considered marital debt, so even if your DH charges it, you are partly responsible (the judge will divide the assets AND debts, so you would still be responsible for your portion of the debt), finally, if you get a separate account and put DH's money into it, it's not going to be a separate account when a judge looks at it.
Also, if you want to separate, for whatever reason, you should definitely do so. But, if you are trying to separate just to avoid one thing (not saying that is the case here!) and you continue to live like a married couple, i.e. have marital relations, live together, continue like you have been, that will be considered by the judge and, at least where I am, you won't be considered "separated."