Dear Jon,
I have read some of your posts and feel for what you are going thru. You obviously love this woman and the mother of your child, but unfortunately the "chaos" of bipolar disorder will continue if she remains unmedicated.

Her actions and the way they affect both you and your son sound incredibly painful, confusing and damaging.
I am married to my BP hubbie for 11 yrs and we have 2 small children, I understand the dynamics and complexities of being with a BP partner with young children involved, and it is anything but easy. Fortunately, my husband is medicated, although not fully accepting of the "illness" and doubtful "if he really needs meds", when he is completely different on them. (he was dx 4 years ago) He would be impossible to live with without them.
I also understand the deep love you have for this person, but honestly she needs treatment or she will continue to act this way, and possibly even get worse. I know how hard this is to deal with as an adult, but the concern is also how her behaviour is affecting your young son.
This is is the nature of BP, complete disconnect to what their actions are doing to their loved ones, it just amazes me that there are people who search their whole lives for true love, in this case she has it, but doesn't take care of it. (you)
I wish I had more advice, but the only advice I have is....get the woman medicated, which I know is her choice and not easy to do (esp. 20 yrs after a dx)!
I can sense the pain you have in your posts, keep praying for peace, strength, guidance, and help for your lady. This has helped me, and you know you are not alone by far.
Best,
4support