Don’t sign anything. You only have 20 days normally from when he files and after he can ask for a default. He could ask for whatever and if you’re not contesting he could get it even sole custody. Get an attorney. Never ever do an uncontested divorce. Even attorneys, hire attorney’s to defend them. Does he have an attorney? By ignoring him he could say you’re refusing to cooperate and so much more. You can ignore him but don’t ever ignore legal proceedings. H
It depends where you are. In the UK, I believe he can request Ballifs to serve you the papers, you might be liable for fees. If your concerns are with regard to the legitimacy of the divorce papers you can have a solicitor look over them. If you wish to salvage the marriage, you need to be open with him before your costs may increase.
IMO if y’all are separated, other than for kids or legal matters, y’all don’t have to communicate at all 🤷♀️