I just want to say that, whether you had an illness or not, I'm sure that no one remembers the incident right now. They don't actively think about it now, it happened two years ago and everyone involved is probably a busy person with lots to do and many things on their mind. That incident, I'm sure, is the least of their worries.

Even if you didn't have bipolar disorder & it was you just being absurd, I would say the same thing because it's true. But in your case, it was your illness that caused this behavior, so really it's not even any fault of your own. It's nice that your professor was understanding about the psychological issues you were going through.

Honestly, we can't change the past, but you know, everything happens for a reason. All you can do is learn from the experience, and keep moving forward. Maybe you can write him a letter or email about how the incident was caused by your disorder and you're in good treatment now and are stabilized, and are trying to make amends for the mistakes you made throughout the more unstable points of your illness.
Good luck!