Your husband was right to hold her to account. But the words he used were out of order and to say that he loves her less is a rather disturbing thing for a parent to say.
I think he needs to calm down firstly and realise that he damaged the relationship with his tactlessness.
I don’t agree with your view that she’s over 18 so you can’t ask that. As parents you have a responsibility to guide your daughter and point out if she is doing wrong. The manner your husband chose to do that in was just very damaging.
Do you have any proof she is having sex with him? Or do you just assume?
I think he needs to calm down firstly and realise that he damaged the relationship with his tactlessness.
I don’t agree with your view that she’s over 18 so you can’t ask that. As parents you have a responsibility to guide your daughter and point out if she is doing wrong. The manner your husband chose to do that in was just very damaging.
Do you have any proof she is having sex with him? Or do you just assume?