Yeah, I can see how Rain-X would make it worse. I was going to recommend Goo Gone or Goof Off, but one of them is an acetone cleaner and you’ve already tried that.
I recommend calling your insurance company and having them refer you to a windshield repair/replacement company. Repairs to your windshield are usually covered with zero deductible, and a repair company will usually come to where the car is to do the repair or replacement. Usually these folks repair small cracks or replace windshields, but they might also have a solution to your problem other than windshield replacement. If worse comes to worst, they can always swap out windshields and then reuse yours after it is chemically cleaned and re-coated at the factory.