I fear that your Son got involved in A Classic Dilemma that we normally see with divorced couples.
During their conversation, Mom probably sent The Message: "If you love me, you have to decide that your Father is bad! There is no Choice!" It's a "forced choice" and the relationship between the two of you, and his relationship with his Mother are two different things. But, I'm betting she pushed him into making that choice. He's 19, and technically an adult, but he's probably ill-equipped to make such an adult decision as "separating behaviors from love and acceptance of The Whole Person." And, realizing that you are not a perfect human being.
You already got The Best Advise. Try to find a Therapist skilled in Gender Issues. But, I warn you that it will probably have one of two outcomes. I have a feeling that once other people find out it's not about playing The Blame Game, they will either change their opinion, or behave like children and walk away from trying to work out The Problems.
Peace and Love, Joanie
