Three questions in one. Heavy!Here is my three cents worth.
As for the haircut, maybe continually suggest to your monster-in-law that she should take part in a charity head-shave, and how a shaved head would really suit her. If you annoy her enough she will either finally get the message, or stop talking altogether. Could it be any worse than the present situation?
All you can do is tell your girl quite firmly that you love her, will be there for her regardless, and are not going anywhere. Ever. No matter what she says or does.
If she still is not convinced refer her to Aunty Karen and I'll tell her to pull her head in.
Title? you could go with "love of my life", because that is what she sounds like.

I hope I can find your twin sister some day.
Karen.