What options do I have when undergoing a chapter while receiving mental care after a deployment?

Commission of a Serious Offense (paragraph 14-12c). The commander must provide evidence of a specific military or civilian offense that the commander believes warrants separation from the Army.
This involuntary separation is not done lightly and not for yelling at a fellow SM (even if he deserved it) Nor given for a fist fight....

If you "snapped" and beat the kid 1/2 to death, or cut his head off with a leaf rake..then there would have been UCMJ as well..and likely a punitive discharge.
In any case, a involuntary separation can be started at the same time medical care or MEB is ongoing. Once the MEB gets so far along (I'm not an expert, and our resident expert is no longer in uniform) it takes precedence over a command directed chapter.

Talk with legal services....STOP talking about it here

The VA has vet centers that will assist any veteran, whether active duty or separated, with behavioral health issues, for free. they have group options or, if you have issues regarding groups, can do one on one counseling - All you need is a CaC card identifying you as active, or a dd214 -I myself have utilized these services and found that they really do help with PTSD and anger management issues - honest advice - get the help you need - The Army is going to do what it is going to do and you have no control over that, what you DO have control over is the ability to get the help you need. Good Luck troop.

14-12c is Misconduct for Commission of a Serious Offense. So is the chapter related to snapping on the kid that had the inappropriate relationship with your wife?