i am a keeper of secrets. My family does not know about my bipolar (i dont live at home, im a grownup

)
My poor younger brother has struggled with anxiety and not being able to sleep for twelve months now (hes being treated for PTSD after a car accident) and my younger brother has said he is bipolar (too). Seems like we have a theme running here.
Am i letting my family down by not sharing my diagnosis??? (my partner does know my diagnosis, but doesnt know much about the condition.
Also i have never ever told anyone how suicidal i get (at minimum four times a year) when my deepest longest depressions hit. when they hit i make my plans, and struggle not to impusively act on them. I have two small children. Normally i have my responsibilty to them to keep me from considering this way out . But sometimes i convince myself they are better off alone. Should i tell my partner? My friends? Obviously i should tell my doc but im not seeing her now.