Hi Donnie, First let me welcome you to the forum here we are glad to have you and I do hope any and all advice/suggestions you get are helpful and supportive.
I have had depression forever it seems and indeed I too push those I most love away from me when I am in one of my depression spells. Lucky for me I havent had one in quite some time...lol! I do take an antidepressant and know I will always have to take one inorder to live a "normal" life...whatever "normal" means but, you get my drift right? I am just trying to say that I understand the behavior of your girlfriend...and your right it isnt so much her as it is the depression.
For each one of us who have this it is different but seeking help either in the way of counseling or medications is the most important step. You cant do that for her, you can encourage her strongly but taking it seriously in your mind is a totally different thing. That stage or point in our lives is different for everyone.
She is very lucky to have your support and encouragement. Please keep us posted on how she is doing and how things go okay?