My friend's ex was a crack addict and went to several rehabs. At first her young son (about 5-6 yrs) really missed his dad and wanted to go see him on family day. She too thought it would be good support and a motivator. Next time?? He said NO! She didn't force it.
Her son is now 20 and says he still can remember that visit and although the first rehab was a cushy one - he still knew something was wrong and shouldn't be there.
After several attempts at getting clean and some sobriety time, he is currently still an active crack addict who has lost everything, including his son.
