It's my DSS birthday tomorrow and it's not DP's contact weekend. Yesterday he arranged with DSS' Mum to have him for the afternoon tomorrow and then overnight. Due to now having him, he wants to throw him a little 'party' (as much as you can have in lockdown!). He wants my DS6 to come to this party, even though he is due to be with his Dad this weekend.
Last night he brought up this 'party' in front of my DS, who of course now wants to go. I explained that it was DS' weekend with his Dad, to which DP said tell his Dad he won't be coming this weekend anymore. I said no I can't do that, it's his contact weekend. He turned to my DS and said 'wouldn't you rather come to a party than see your Dad?', to which my DS said yes. DS then spent literally all evening telling me I was mean that I was making him go to Daddy's when he wants to go to DP's instead.
I said to DP it was unfair that he put me in this position, especially in front of my DS, and he just shrugged his shoulders and said that I shouldn't send DS to his Dad's.
Am I wrong here? I feel like I've been made in to the bad one when actually it was always DS' weekend to go to his Dads and the party was only decided last night.
(FYI - I say party but it's only balloons, cake, presents etc with no other people other than the ones on zoom. He wants my DS there so that DSS has someone to play with).