Good morning, I would like to help with your issue today.
I do understand that you are concerned for your daughter with her dating this troublesome man. It amazes me as well to see the large number of women (and sometimes men as well) who lower their standards of dating; and so often it appears to be because these individuals have low self-esteem; this could very well be your daughter's issue. Do keep talking with her; as difficult as it may be, do your best to remain calm during the conversation and listen to her in return. Let your daughter know that she is a beautiful and talented young lady who has her life ahead of her, but that her current relationship is not what you feel is best for her. Let your daughter know that she is worthy of better, and that you suggest that she leaves that fellow behind.
I also suggest that you recommend a therapist for your daughter, who may be able to assist her with her issues of selfesteem; Good Therapy.org has a large list of therapist to choose from by your zip code or area (they are international as well). If you do need any further assistance with your question, please do not hesitate to message for me; I will be more than happy to help. Thanks. "earthsister."
and here is the actual link to Good Therapy.org: http://www.goodtherapy.org/