Moving out now does not commit you forever. You can change your mind at a later date if it seems wise to do so.
Right now, you have a plan in place, you stated your intention, and I think it's important to carry out your plans. None of us has a crystal ball to know the outcome of any particular action we take. There are ALWAYS "what ifs". If you wait until you are certain what will happen, you would never make any decision or any change.
You have thought this through. If you don't do what you have said you would do, why should he take ANYTHING you say seriously? He views it as just another empty threat, just a manipulation by you to make him do something he clearly does not want to do.
Up to you, but I would consider the above carefully before you decide to give him one more chance.