It's a tough place to be, to still feel like you can't cope with stress even with meds. I wish I had words to help, all I can do is hope that you make it through this tough time unscathed. Sometimes you have to just be able to tell family that you aren't "feeling well" when it comes to major issues and step away when those tough conversations happen.
Of course easier said than done, and I have had major melt downs in the middle of conversations that have nothing to really do with me. I get overly emotional so I know now I just have to walk away.
Good luck, I hope your able to equal out soon.