AITAH for not wanting to spend my birthday with my kids ?

I (F, 37) have three kids with my ex-husband (M, 38) and one toddler with my ex-boyfriend ( after my divorce) . I get along great with my exes. My ex-husband is a good friend of mine; he is an amazing dad and also helps me every time I need it. He has been dating a lovely woman since our divorce (long distance).

He invited me and all the kids, including my toddler, to dinner at a really nice restaurant last night for my birthday. I told him I prefer if he takes the kids instead so I can have a kid-free night to myself. He suggested, 'Why don’t we go for the dinner since I already booked the restaurant, then I can take the kids for the weekend?' (It’s my week with the kids, but he suggested it). I agreed. Later, my best friend suggested going for drinks for my birthday since she is going away on a trip the next day. I loved the idea because I just wanted some kid-free time for my birthday. So, I dropped off the kids (including my toddler) at my ex-husband's place so they could go to the restaurant and went out for drinks with my friend. When I told my friend, she said it was a rotten move since I should have checked with my ex. I told her that he would have gone to the restaurant with the kids anyway, just not with me now! My ex didn’t say anything and still took the kids (he dropped off the toddler later, so her dad will pick her up later today).

Am I the a**hole for wanting to have a kid-free birthday? If I had told him, he probably would have guilt-tripped me to go to the restaurant with him.