My son only wants his dad!

I have a 3.5 year old boy. My exhusband and I divorced in December. It was a necessity- he was too comfortable putting hands on me while angry in front of our child. He was awesome at transitioning before. We have had a 2/2/5/5 since October. Near daily over the last month, my son cries and cries for his dad. He tells me he only wants it to be Papa’s turn. He cries when I pick him up from daycare, even when it’s been my turn and we talk about it in the morning and he seems okay. It’s starting to really hurt my feelings. My home is loving and has lots of toys and we get out of the house regularly to do fun stuff. I make food he likes. We read lots of stories together. I just want to cry when he is disappointed that I picked him up or cries when he sees me coming.