Please, be encouraged to seek some counselling to help with your present state of mind. Just because she said so doesn't make it true, and there are ways to help your self esteem and belief in yourself recover.
Her lies crushing you means that she is winning, and she possibly doesn't give you or your feelings a second thought after all these months. Reclaim your life!! It doesn't have to be so miserable, but you need to work at making it better.
We can encourage and support as much as you need, but baby steps to your GP to ask for mental health assistance is a good start. Feeling so low for 3 years is hard, but it can get better and you don't have to let this episode make it worse or get the better of you.
Please talk to your doctor. I can promise you that a good GP won't be shocked or judge you. They've probably come across your kind of situation before and may have lots of good suggestions to make.
'Mongolian Warriors had the courage of lions, the patience of hounds, the prudence of cranes, the long-sightedness of ravens, the wildness of wolves, the passion of fightingcocks, the keenness of cats, the fury of wild boars and the cunning of foxes.' BE A MONGOLIAN WARRIOR WHEN DEFENDING YOUR INNOCENCE!