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I think he's past hypomania and well into a manic episode. You've got great insight and observational skills! The best thing to do is to get him to a doctor - ANY doctor. They can give him meds to try and chip it down a notch so that he might be amenable to further treatment. It's also usually easier to get into see a GP than a psychiatrist, and time is of the essence in this case. Even a walk-in clinic is a good start.
I would write out his symptoms in short form...in a list and at the end of it, say that you can see he's hurting and want what is best for him. You'd like to take him to see a doctor for help. Keep the focus off arguing about the symptoms and what they mean...instead, focus on how he seems and how much you see different, how unhappy he seems, how much you care and want him well. Say things like, "I see you doing things that I know aren't really you." When someone is this far into it, they're usually paranoid as well, so you have to try to work around that a bit.
I would also contact his mother and let her know what is going on....she may have some influence as well.
He's got to be feeling horrible right now, and these things snowball. If it gets to the point where he really is out of it, call an ambulance and have them handle it. They do this all the time and know what to do. They can get him to an ER if you can't. Some people wait till they're drunk and then take them to the ER. During the wait, he'll sober up and show the mania, but the staff will believe you if you come in and communicate like you've done in your note. You make perfect sense and are hitting the right spots.
Breakups made during times like this don't really count, so I wouldn't put much energy into that. Do what you can do, but also you have to understand that you may not be able to motivate him to get help. If that becomes the case, you'll have to let him go.
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