I'm so sorry to hear about your problems with depression. I totally agree with D-Man, that you should seek help for it right away. I'm sure your parents would be supportive of you finding a way to regain your equilibrium and regain a positive and energetic attitude.
I'm not a regular member of this forum (I am more regularly on the GERD forum, and visit the Allergy/Asthma forum every so often), but am trying to help out a moderator on our forum who has a family emergency.
I wouldn't attempt to respond to every post here, but I also have mitral valve prolapse, and understand how scary that can be. Fortunately, I never experienced depression as a result, but until I was diagnosed, I suffered from a great deal of anxiety.
I quickly searched MVPS online and found the following link that addresses depression: http://www.mitralvalveprolapse.com/depression.html
You may have already seen it, but I thought if you hadn't you might find it helpful.
Good luck, and please seek help, so you can get back into a happy and positive mood.