what do you do when you know your friend is having some problems, but you only know the severity of the problems because you found out sort of by accident? and if you decide to talk to her about it, what do you say?
Take the safe route...pretend you don't know the full story, and ask him/her if they are okay. Ask them if they need to talk about anything and let them know that you are there for them to talk to. I wouldn't say upfront that you know what the problem is. The person might think that people are talking bad about him/her behind their back. Take the friend approach by just letting them know that you are there for them. The friend in need will thank you later for it. Hope this helps somewhat.