I'm truly sorry you're feeling this way.
You can't change the past, that's true. But you do have the present - if you try to be in the present as much as you can (you might want to consider trying some simple meditation exercises, like focusing on the breath), that will help.
Do see your counsellor, and if you can, check out
EFT Provides Impressive Health and Emotional Freedom--New Discovery Often Works Where Nothing Else to learn about EFT (Emotional Freedom Technique) - it's been discussed on many of the other threads in this forum, and it's helpful both with depression and with removing limiting beliefs.
Can you get hold of Bach Flower Remedies where you are? They work more slowly than EFT, but they do support the process.
Take care.