Does him defending his ex mean he Still cares?

Been married for 8 years; husband’s ex wife has been a source of contention in the beginning as she made our lives hell. He allowed some of it since they shared a child and she would threaten to turn the child against my husband or increase child support if he didn’t oblige. Our marriage was great except for that and it was the cause for all of our fights.

Since then, ex wife did some trifling and scammy things and they have no more contact. What he has always done that bothers me however, is defend her in some capacity.

Example: we got into an argument and it came up about his first marriage vs what he does in this marriage. He commented he got to do as he pleased, and I remarked it was cause she was getting hers on the side (something she admitted to me). He flew into a rage and said he doesn’t know that for sure and can’t say but me taunting him with that makes him feel stupid and emasculated for my taunting him.

I was cheated on in my first marriage. My present husband could tell me my first hubby was screwing everyone and their sister and it would not bother me as I don’t have feelings for him anymore. It’s no blow to my ego as I got out of the marriage. So, why does he care to defend his ex? Does it come off as still caring and not wanting to believe she would do that, or is he onto something and it’s a blow to his fragile ego? He does not ever talk about her, look for her, want anything to do with her. He’s very upfront with me and not the type to stick around if he’s not in it 100%. The defending and the anger over it have me fd up though.

Give me your thoughts please.