The only thing that I can suggest is look back and think about what exactly had changed. Is it something that you can change back? Is it something you have to a accept? I know that the serenity prayer helps some with this. I'm not particularly a religious person so I prefer my mantra which is "I'm a human I make mistakes. It's my choice if I learn from those and grow. But no matter what I must accept that I can't go back and change those mistakes." We as humans make mistakes all the time. It's part of what makes us humans. Now that being said being the person you are (be it bipolar or not) you need to accept you first and foremost. You cannot change a zebras stripes nor a leopards spots. Having an illness or disease is part of what makes you you. You can learn to change your thinking (another aspect of humanity) so that your "mistakes"don't interfere wroth your life.
I know not everyone will agree but mistakes can be good or bad. It's all in how you look at them. I hope this helps you.

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