Why do you need them to respond? No offense intended, but they are not the problem here. They are who they are.
Please ask yourself why in the world you contact your ex at all, what is it about you that needs a response, and why you can't take the hint that his family doesn't want to interact with you anymore? It may hurt, but it is what it is and it gives you a chance to go, unencumbered, on with your life.
May I suggest taking this hint from your higher power, ceasing your attempts to contact your ex or anybody in his family, and get on with your life using the lessons you've learned from this relationship?
I truly wish you the best. Take what you want, if anything, and leave the rest.
Cyranaok
P.s. I'm going to practice my recovery and not be offended if you don't respond.