Why? Because he's mentally unbalanced, or at least sounds it. And a total buzzkill. Way to ruin the weekend, asshole.
As I read your question I thought about scary movies where there's always someone on the phone yelling "Get out of there! NOW!" to a friend in danger on the other end. But it's too late--the ax murderer is right behind them.
How do you know he's bipolar? Has he been diagnosed by a doctor? Does he have medication that he refuses to take? Or are you just guessing that he is bipolar? Not that it matters--at the very least he has serious rage issues, if not much deeper psychological problems. If he hasn't been diagnosed, he needs to get his angry ass to a doctor, pronto. If he has been diagnosed but won't take his meds, then he's both disturbed and stupid. For him to ignore a problem that you both know exists is the same as saying he doesn't care what happens to either of you or your relationship. And that's just unacceptable.
We all have bad days, sure, but he crossed the line. Whatever issues you two might have about money, nothing warrants that kind of abuse.
You didn't ask me what you should do, but I'm going to tell you what I think anyway. I would absolutely not marry this guy until he gets his head screwed on straight. Whatever you are experiencing now will only get worse once you're married. What happened Saturday will happen again, and it will probably be worse next time. And even worse the time after that.
In fact, it were me, I would have already been moved out by Saturday afternoon, but then, I have a very low tolerance for bullshit and I know several people who own a truck. If you have somewhere else you could live for a while, though, it's something to think about. Unless you like sleeping with one eye open.
I would tell Yosemite Sam that you won't marry him until he takes care of this problem. It's not an ultimatum and it's not blackmail; it's you protecting yourself from someone who is emotionally unstable, and preventing a mistake that will affect the rest of your life. The guy needs help; if he won't do it for himself, maybe he'll do it to save your relationship.
If not.. get out of there. Now!
Yikes! Yeah, I would have been packing my bags that same Saturday too. I wouldn't want to stay with someone who screams at me in rage and obviously doesn't want me around. I would feel threatened in that sort of situation, and I wouldn't want to live my life in terror.
Good advice, Cary.
Something to consider - bipolar is genetic. This trait could very well be passed onto your future children with him. My husband wasn't diagnosed until after we already had three sweet little boys. Now, I try to 'help and support' my husband - but I fear what may happen to my little boys if they have inherited the bi-polar disease. I'm sure it is easy to look at your fiance and think "I love him and I'll stand by him." I understand that. But I wouldn't wish it on any child. Medication does help (my husband,) -- when you can get him to take it. Nothing like not knowing what tomorrow may bring.
Something to consider - bipolar is genetic. This trait could very well be passed onto your future children with him. My husband wasn't diagnosed until after we already had three sweet little boys. Now, I try to 'help and support' my husband - but I fear what may happen to my little boys if they have inherited the bi-polar disease. I'm sure it is easy to look at your fiance and think "I love him and I'll stand by him." I understand that. But I wouldn't wish it on any child. Medication does help (my husband,) -- when you can get him to take it. Nothing like not knowing what tomorrow may bring.
Being mentally unbalanced and bipolar are two different things. This is what psychologists technically term being "emotionally labile," or being an emotional see-saw in layman's terms. Bipolar Disorder, which comes in three different types, is a cycle of depression and mania, with periods typically lasting days or weeks though the depression can last years occasionally.
*sigh* As a psychologist in training, seeing the term bipolar misused all of the time has worn thin.
That said, I do think that there needs to be diagnosing and/or therapy before marriage is even considered is the asker is planning on staying. In all honesty, I would just bail.