Well, if I were you I would wait for an opportune time to tell them you have bipolar, I wouldn't really give out the information about the BPD though, until at least after you gauge how they react to your bipolar. Don't just show up to work and announce you have bipolar though, just wait until your coworkers start talking about bipolar patients again and gently chime in, "I'm bipolar too, I understand how difficult it can be..." I don't think they will necessarily judge you, and if they do then they're in the wrong line of work. Although it's really none of their business, so just open up about it whenever the right timing comes along in a conversation. You can also say something like, "The fact that I have bipolar makes it easier for me to work in mental health because I know how it feels."