My first Mil was an utter delight and she/I were so sad when I parted from her son, even though she thought I was right to do so and apologised for his behaviour. Lovely Mil.
Had lovely relationships with nearly all my ex boyfriends mums too 😊
My Mil now.......
nasty, spiteful, negative, drunk, racist, snobby creature. She was a pretty grim mother and my DH sees her rarely as she has not a positive bone in her body but he wants a relationship with his dad.
I have done my best to be kind, understanding, build a respectful relationship etc. However, having been told to "get on the boat back home" (my family aren't English), having my adopted daughter slagged off and told "she's not real family" having been told I couldn't have a wedding dress and should just wear a navy suit to a registrars office amongst many. Many more things... yeah I don't like Mil my and don't see much of her at all.
So, it's not Mil status that defines whether I like a person or not, it's their behaviour.
And if people have never experienced the damage a bad Milcan do, they really shouldn't berate someone in the throes of dealing with one.