Separation agreements are always cleaner than going to court. Problem is you both have to agree.
The only certain thing about going to court is the uncertainty.
It is hard to say what a judge would do. I think you have the advantage. He left you with the kids. You could easily get temporary custody since they are with you. Temporary custody tends to have a better chance of becoming permanent custody. He would have to travel here to fight you. With temporary custody comes child support. That too has a tendency of becoming permanent.
Same thing would happen if you filed for ED (Equatable Distribution). He would have to fight you here.
All of this ignores the fact that you would be paying an attorney to do all of this for you. You know they don’t work for free.