Hi there, I am a bipolar mum (among other things). It's not something I'm ashamed of, although I'm not exactly proud of it either iyswim. So, I only discuss it with couple of people in RL.
Although I'm stable on my medication, and I have some group art therapy coming up, if you have bipolar you will know that things can still get a little intense, even when you're well. To be honest I often feel as though it's like the sword of Damocles hanging over me. Even though I'm much more stable and have found coping strategies, I know I'm not immune to episodes.
DP is very patient and supportive and he has been my rock. I had an episode of psychotic depression about two and a half years ago, that I think was bought on by the stress of moving twice in one year, relocating, having nasty ongoing health problems, some surgery that went badly wrong and being bullied by my boss because of having to keep taking time off work. It just tipped me over the edge. Looking back I can see that I have always had episodes of mania and depression since my mid teens.
I'm lucky enough to live in a rural area with a brilliant local mental health service and I am about to be discharged by my CPN and psychiatrist. I do feel as though things are on the up. I now have a clean bill of physical health and being discharged is like having a clean bill of mental health too (as long as I continue to look after myself).
I have been very frank with DS (13) about my bipolar. My father is bipolar and has psychotic episodes and I only found out this out 5 years ago. DM and DF (both were teachers) had always tried to keep it hidden, although I knew there was something odd about DF's behaviour! In a way I wish they had just been open. It just goes to show that even 'respectable' people can be bat-shit crazy behind closed doors. 
I don't think you have to make a big deal about it, but being honest means that kids don't spend their lives wondering what they have done to cause such behaviour.
Anyway, ramble over. If you want a chat... 