I'm frustrated with my situation with my son's dad. Yes he's a decent father. But he's selfish. He…

I'm frustrated with my situation with my son's dad. Yes he's a decent father. But he's selfish. He wants to go back to court to have his child support reduced(which, besides what's been claimed by maintenance enforcement, he hasn't paid).He owes almost 3 years of back pay.

On Sunday night my boy got the flu. Woke up at 9pm puking, diarrhea, fever. Once I got him cleaned up and settled on the couch with me, I messaged his dad to let him know. As soon as I sent the message my boy puked again, and I updated his dad again. Every time he puked or his temp went up I let him know up until about midnight when I told him that his visit for the next day wouldn't be happening as my boy could hardly make it to the bathroom to throw up let alone be able to make the 20 minute drive to his dads, I also didn't want his girlfriend's kids catching it. My boy didn't fall asleep till 4am. We woke up to messages from his dad. Starting with "take him to the doctor" followed by "I'm perfectly capable of taking of my son" "it's my day" he eventually agreed but it's like...are you feeling kidding me?! Your son is SICK with the FLU a doctor would say give him Tylenol and let him rest, which is what I had planned to do whether he liked it or not. But all he cared about missing HIS day and HIS time. Just like one sleep over my boy woke up screaming and crying for me so he called my mom (my phone was disconnected), who offered to pick him up because I was working an event. "NO. That's cutting into MY time with him" like...seriously? Now for months my boy has been fighting going to his dads. "I dont want to go I hate daddy" but its court ordered. Now my boys been having serious emotional issues the last few weeks. Tantrums, violence. His dad denies that anything is wrong. That my boy is perfect for him pretty much all the time. But it's gotten to the point that I want to put my son in therapy because he's gotten violent! He tried to punch my mom in the face this morning because he didn't want to go to his dads. His tantrums are already bad but they are worse when it comes to seeing his dad but he won't do anything to help me get to the bottom of this. I'm concerned that this issue has stemmed from being forced to see his dad or that something may be happening there that my son won't tell me. Aside from therapy, or sticking a recorder of some sort in my son's bag to hear what goes on during his visits, I don't know what to do! This morning's fit was so bad I was in tears.