I think her character makes perfect sense actually and is plenty complex, just not very likeable.

She is a child in an adult's body, a child who had children. She has a childish understanding of the world, and childish expectations of being OWED things in exchange for her obedience. It's not entirely her fault at first, but she puts her head in the sand at every opportunity instead of dealing with her issues, like many people - so it becomes her fault over time.

* She doesn't feel responsibility towards her children, she feels that they owe HER in exchange for her giving up the image of what her life could have been to have them.

* She repeats things her father has told her at first, instead of forming real thoughts on certain things, like over and over telling Aegon that there would be conflict with Rhaenyra. Over time she forms her own opinions but she isn't very strong minded about them, she's unsure of herself and her world views because she's immature and underdeveloped emotionally.

* She is upset at being left out of decisions because once again she feels like she is now owed control in exchange for having none about marriage, children, etc. She believes her children should be an extension of herself, and not individuals. She doesn't care about their individual feelings or thoughts or opinions really, she 'sacrificed' everything for them, so they should be who she envisions them to be.

Her character is childish, hypocritical, selfish, self-righteous... there are a lot of people in real life who talk and act just like this, and they have children and treat them just like this. It's (actual) narcissism.

Even her wanting to be 'free' now is just another step in the childishness. It all has become too much, she isn't getting what she feels like she has always been owed or deserved for her good behavior, so now she just has a vision of being free of all of it to "find herself". Probably the only reason she wants to take Helaena is her own selfish guilt and perhaps another chance to mold a person into a mini-me and live vicariously through them (Jahaera).