Welcome Kristin
Sorry to hear you're having problems. I've had depression since i was 14, so i know the struggle.
There is private messaging. There are various ways to start it. If it's someone in a forum you can click on their name and an option should show.
You can go to their profile and message them from there.
Adding people as friends can make it easier, if you message the same person frequently.
Lastly you can go to your PM box and start a blank one there, if you know how to spell the persons site name.
I know there have been some issues with the PMing feature. I don't know if it's been glitching, or they made changes.