I like her. Yes, she's often miserable and can be nasty when bitter or hurt (like when she drove Ricky away because she was upset about David) but that makes her multi layered and she's had a hard life. She's made a lot of mistakes but generally rolls her sleeves up and gets on with it to do the best for her famiy rather than expecting the world to owe her a living.
She can be overly fond of playing the martry but i think she has necessary had to put her own needs last so much that it has become second nature now and she doesn't know how to break the cycle. When she has gone for her own happiness, it has generally gone horribly wrong - like with Dan.
Re turning her back on her children. Bianca, i do kind of understand after the Dan business. Bianca was a grown woman who had made her own decisions. Sonia is much harder to forgive, she really did nothing wrong and fact is it wouldn't have happened (carol not supporting her) except coulson had left the show and they wanted to keep Sonia in. That doesn't mean we can wipe it from history, it did happen but it was out of character.
I also do think that Coulson is the best actress in the show.