What can i do to alieviate the pain?

My gf an I got in a fight while she was pregnant. She left me for her ex hiding her pregnancy till she had a miscarriage. She says she still loves me an I haven't stopped loving her but she won't leave him. We have so she's cheating on her Bf an it bugs the crap out of me. She says she wants me but she wont leave her Bf. It's been almost two years an I can't get over her. I'm sure having a child with her an then losing it plays a huge part since we new it was a girl an named her. What can I do to fix this? It's driving me further an further into depression an causing me to be reckless when spouts of emotion erupt. I had a $67k medical bill for trying to kill myself. I need help.