I agree with pippi you are not weak. I experience this aswell when he tries to contact me or sits outside the house to pick up the kids in a place where he can see me.
Stay strong if you are like me if you respond you will fall apart and lose all control do you feel better when when you have no contact?? If so don't respond or you will be sucked back into the vortex of misery that addiction causes!!
Focus on you not him