You’re right to take a big step back. No, people with bipolar disorder are not necessarily prone to rages, especially if they are or have been in treatment. It’s too glib for him to say “My bipolar makes me do it” and it’s a disservice to others who are struggling with the same illness.
My guess is that he is still recovering from his marriage. He’s only been out of it a little more than a year. The way he reacted says to me that there are wounds that still need to heal. Instead of looking at his own reaction and taking himself off to a therapist, he wants you to take responsibility for an affront that is a product of his own imagination run wild. I don’t think he is necessarily a “coward” as you put it. I think his hurt and anger make it hard for him to see you for who you are. It may be that he is responding to you as he did to his wife.
As charming as he can be, he has work to do before he is fit to be in a relationship with anyone.
I wish you well.