ONE good thing my lawyer taught me, never say I'm fine or I'm ok, if I'm not! I don't say it. I have other phrases that I've developed, based upon my own rating scale of how I'm doing that day. Maybe you could also do that? It's not good to feel like you "can't" share and have to tell everyone what they want to hear.
Feel free to tell others, when they ask, "Things are tough right now, but I'm working through them."