unfortunately you can not make an addict do anything they do not want to do. So if he does not want to leave, unless he has tried to physically harm you - I am not sure that there is much the cops can do.....
As stressful as it is - try to take a deep breath and at least be thankful that he is high in the garage and not in the house....
Have you talked to a divorce attorney? If not, you might want to find one and be completely honest with them on what is going on. A family or divorce attorney is going to be the best one to give you accurate advice on what you can and can not do....
Iknow nothing we can say at the moment will really provide much help but know that there are an awful lot of people who are out there thinking about you tonight.......
Hugs......