Respect for parents

I have been listening since childhood that no matter what, we have to respect our mothers. But what if the mother is characterless? My mother secretly met a man and had very dangerous plans with eloping with him. I somehow came to know this and informed my father. My father spoke to her but she is not willing to stay back and marry the other man. How can I respect such a mother? She has no affection towards her children also. I have been suffering a lot past few months. Please guide me.