Nedd Advice PLEASE!!!!!!!

Hello I am in hopes that anyone at all will be able to help me in
regards to a problem I having. My husband and I have been separated
now for a little over a year and our divorce will be finalized
shortly. We have an 8 year old son whom we share. When I come to pick
him up from his dads he throws a fit and screams and cries and doesn't
want to go sometimes. Once I get him in the car though he is totally
fine and we have a great time together. I am at my wits end with this
and it breaks my heart that he acts this way towards me sometimes. I
am not sure what to do I was just wondering if maybe anyone out that
had any advice at all or thoughts about what could possibly be done. I
don't like seeing him get upset but I need to have my time with him
too. Any advice or thoughts would be greatly appreciated. thanks,