Does my partner still have feelings for his ex fiancé?

So I’ve been with my partner for a while now and noticed he often talks about his ex partner. She was domestically abusive to him and she now holds the two kids they had together against him. He’s now perusing court action to get access to his kids and he’s constantly heart broken at the thought of not seeing his kids. I have held and supported him through all of this but recently I’ve started to question wether he still has feelings for her. He often sticks up for her in arguments and whenever we talk about the domestic abuse he often says “but she had a hard life” so on…

We were having a conversation today about me and him getting engaged he’s made it clear to me that he does want to propose soon but mid conversation he started talking about when he proposed to his ex and the ring he got her and then started showing me pictures of the things the hotel set out congratulating them on their engagement.

I don’t know if I’m in the wrong but it’s upset me and made me feel really uncomfortable.

His ex was messaging him that she still loved him and wanted back with him at the start of our relationship and he told her that he had moved on and was happy with me and only wanted a relationship with the children.

I guess what I’m looking for here is someone to tell me am I being crazy? Does it come across like he still has feelings for her?

I have straight out asked him and he says he doesn’t but of course he wouldn’t admit that to his new partner.