Man, have I been there, done that with-my difficult child 2. He was not bipolar but has suffered for years with anxiety (five inpatient hospitalizations, the last one a year ago for six weeks), mild depression and ODD. His anxiety took the form of physical aggression toward me and our younger daughter. When I left his dad I took the girls with me because I knew he wouldn't cooperate with me in any shape or form. And, like your son, his teachers adored him, he had friends, other parents marveled at what a good kid he was. Played sports, although he would often become anxious about performing in front of others.
About calling the cops: only threaten to do it if you're going to do it. I've done it twice. First time it was to get my kid transported to a hospital (they ended up not admitting him) after he struck me in the back at age 13. It was part of a "safety plan" cooked up by his incompetent psychiatrist to get him admitted to a hospital and then to long term Residential Treatment Center (RTC). Well, all I got for my trouble was attitude from the cops. It was very traumatic and embarrassing. And the hospital said he didn't meet the criteria for admittance. Second time was a year ago when he knocked over my big tv and broke it, then started trashing my house. He ran away before the police officer arrived but he was arrested later at his dad's house and went to court. Got court-ordered probation, placed in a hospital for detox from weed (he was smoking three times a day at that point) and when he came home got home instruction from the school district so he wouldn't be with the peers that he often did drugs with.
So, bottom line, safety for yourself and any other people in the home (particularly minor children, I nearly lost custody of my youngest because I wasn't vigilant enough about keeping difficult child 2 away from her when he was raging) is paramount, and you have to have a plan.
sounds like you need to get the diagnosis/medications part straightened out. If a child is possibly bipolar, no behavior management in the world will help until the brain chemistry is stabilized. None of my kids are on medications right now. Could they benefit? Probably, but at age 16 and 19, if they aren't cooperative re: taking it, you are wasting your time and energy. Like an earlier poster said, kids this age are great at undoing everything you are trying.
None of this helps a marriage. Mine didn't end because of my kids' significant problems (ten hospitalizations between the two older ones in six years, drug and alcohol use, theft and damage of my personal belongings, physical assaults,etc.), rather, the toxic marriage worsened the inherited tendencies towards mood disorders. There is a lot of alcohol abuse on my side of the family, and severe depression on my ex's side.
I wish you the best, keep coming back here. More will be along later to help and put their two cents in.
One thing I can tell you as a veteran of the troubled teen wars, is that if you and your husband are going to parent your son together, you must be on the same page. My kids have elevated playing my ex and I against each other to high art.