You can block him on Facebook, that way you won't see him. He won't see you either, but his friends and family will see your GAL'ing activities and probably mention it to him. I personally think I'd either just block him or deactivate my account and forget about GAL'ing to get his attention, but instead focusing on GAL'ing for your own sake. Do it for yourself. Pursue your own interests, what is going to make you happy, or at least distracted enough from your current problems to maintain your sanity. Whatever can get you through the day, whatever can keep you interested in life and not falling into too deep of despair. As you feel stronger and more detached you can change your plan, but right now you need to get through each day with as much self care as possible.
I dont think you need to go so far as to block him. Why create drama thats not needed? I would just unfollow him ad anyone that may trigger you - his parents, his close friends. Then you still show as "friends", he wont be the wiser, and you wont have to see things that will hurt you. Plus, he can still see all of your posts.
