Not only mothers, fathers as well or maybe they would be even worse if they are/were a bit of an asshole as well (like the old saying goes about trust and your own intentions). Like I said I can well see Millie storming off and do something foolish in future, unless someone she might trust for whatever reason would interfere on MC's behalf. (Maybe Valerie if she knows Millie as well from past or someone else closer her age.)
It's probably going to take a lot of people to convince Millie but I agree, I see her doing something foolish.
If it was me i'd have gone to the media. I know he has people praising him but you don't need everyone to believe.
There are always people wanting to tear down the successful and those would latch onto any scandal put forward and that little seed would grow.
If I personally thought someone was mistreating my babies I would go above and beyond to ruin their lives and get my kids away from him/her if they had kept putting me off like they did.
Not only the Millie thing though, it has made Jaime and Liz look like the worst kids ever. Rather than make sure the woman that gave birth to them and raised them was okay they shut her out, put her off and ignored her. They just made a bad situation so much worse.