Of course you help when your child is at risk and putting others at risk. The question is, what is the plan? What is his treatment plan? You've mentioned medication. Is counseling, family and/or individual, involved? And if it is, it's time to regroup and find what works. If not, find someone pronto.
You may be able to talk him down while his mother quakes at being told he hates her as he rebels against her. But more help is needed than he's currently getting. Your son needs outside help beyond what he is currently receiving. Your son needs help. And it's heartbreaking to read of his pain.
Good job with the boundaries, of directing your divorcing spouse on bedtime. Consistent sleep is one of the best friends your son can have. Make it a mutual priority to do what it takes to put your son in the best place possible to deal with the chaos in his life. No ego allowed.
*hugs*
PS.. just saw Kalni's post. Continue defining and refining your boundaries, SG. Continue to let her know her personal life is not of interest. Otherwise you ARE the consolation prize.
Drop the timeline, putting two and two together, the 'aha, she asked me for a date when things went sour with the new guy'. Keep your mind focused on your favorite frontal lobe real estate.. sex, if that's what works for you. Keep her personal doings and emotional drama outta there.
