father-son relationship

my middle child, an eight year old boy, has recently stopped contact and speaking with his dad (my ex-husband. the reason for this (in his words) is that his father hits him and is mean to him, and that he has given him several chances but the he does not change. i understand my son yet i feel i am caught in the middle when dad’s afternoon or weekend comes around. his father is pleading with me to convince hin to give yet another chance and my begs me not to go to daddy’s house. the other two children (my 11-year-old son and 4-year-old daughter) complain to me that they are upset my their brother’s behavior and that they feel he dominates all conversations with this topic and arguments about it when he does join them for a couple of hours with daddy.

here are my models on this issue:
c = son is not talking with dad and wants to stay with me always
t – i empathize with him but feel he should solve this with his father
f = frustrated but compassionate / i do not want him to experience violence again
a = i give in
r = i am in the middle and never get a break / no solution with dad

c = son is not talking with dad and wants to stay with me always
t = he must solve this with his dad ??
f = afraid he with be severely hurt by his father
a = convince him to go to dad’s house but feel worried and guilty
r = ?? i don’t know but i don’t feel ok with this

can you please help me with a better intentional model? i don’t want to risk my son’s safety but i am not ok with being on call constantly in lieu of him finding a solution with dad…