I suffered in silence as well and never told anyone about those thoughts. I was found attempting and after a 6 week long Psychiatric Hospital stay I was diagnosed with BP in 2007. Learn from my mistake and let someone know when you have those thoughts (even if it's just a Pdoc, therapist or GP). I know it's hard, but the alternative can be very dangerous.

As far as disclosing about your diagnosis it's certainly a personal decision. I find keeping secrets stressful, so I made the decision to be open about it.