DS - I am sorry to hear about your situation and that you are struggling so much. I cannot imagine how tough it must be for you to not see your little boy...
You mentioned you had joint legal custody, but what about physical custody? Is that also joint? What is your visitation / custody schedule? You can always enforce that in court if your XW is denying you access to your son. Consult with your lawyer.
I agree with the above - your XW's new H has issues and you should be concerned about how he treats your son...
Keep posting and sharing so you can get support and please talk to your L and get the help you need to deal with this situation. You will start feeling better and more empowered.
Good luck!
Me & H: 44 D7, D6, S3 Together: 20y, M: 17y EA: 11/13/10, Sep: 12/23/10 EA becomes PA: Spring 2011 H filed for D: 09/06/12 D Negotiating began 2/15 OW seemingly gone on 3/15 Still negotiating D