H.Z.
Your son must be your first priority...especially where safety is concerned. For a while I had both of my boys (one of which was a runner) on safety harnesses...for their own safety. We got these cute monkey looking ones at Walmart. I also took them daily to a very large farm to let them "run". This way I was able to train the oldest in a very safe environment when he could run and when he could not run. It worked for us.
As for your husband...you guys need to be on the same page when it comes to this stuff. Your son will pick up on the nuances in no time and try and work it to his advantage. I don't know anything about your situation, but I think therapy is always a better way than to separate immediately. I was a bit confused as to why the child would automatically go to your husband full time...but as I said I don't have all the info. Good luck with all the stuff you are obviously dealing with!!
H. Z. (SAHM 5, 4, 14 month old boys)