Sorry to hear about your situation.
I definitely agree that it's hard to live with a na mahram under one roof. I will suggest the following to put a rest to the issue:
1) Make sure your communication, and the tone you use to speak to him should be polite and respectful. This is a sensitive issue and needs to be tackled that way. Harsh language can only escalate the matter further.
2) Sounds like your brother in law is in Dubai for a purpose. Do some ground work and see how you can help him with his aim and also try and see if there are other living arrangements that can be made for him. Kindly put forward the option for your husband to look into.
3) Please speak to an adult, counsellor, or an Aalim to help you both out. Someone who will explain and adress both your concerns.
4) Prayers. Pray a lot for your B.I.law's success. Pray he finds a good job and a good house to move into inshaAllah. Allah wil bless both I.e. him and you altogether.
I hope this was practical..