It is very common for someone with a mood disorder to be irritable and irrational. Even depression brings about extreme irritability which the person may not realize even exists. You should approach this issue again maybe with some material on the symptoms of depression. Timing however is everything. You are not going to gain her cooperation by engaging in a power struggle. You have to suggest this when she is calm and focused. Otherwise you will be met by deviance. I would have specific information such as symptoms and even names of psychiatrists in your area. Sometimes when people are at their lowest they are more receptive. If you think she is willing then discuss the symptoms together. Do not ever make suggestions when someone is angry or irritable. Everyone has good days and that is your time to approach this subject. You can't make her want to get better. After you have made this offering you have to back off and let her make her own decisions.
I want to help her and the children because it's affecting all of our lives. If I give her the research and suggestion of a few psychiatrists when she's in a great mood but she rebels. Should I try again if she doesn't seek help?