Five year relationship
So, I've been with this guy for five years. Things have gone up and down in those six years. He has lied to me countless times, he is a heavy drinker, and he can be the most hurtful person you could ask to meet. At the same time, he has amazing days where he's completely honest, caring, and wanting me to be around. We were supposed to be engaged. But he called it off three different times. I feel like he's just using me as a fall back plan because he knows I won't leave. Opinions?
It seems like you have a relationship where most of the time it's damaging and you hold on waiting for the good days. Don't live a life where you are in constant turmoil and only holding on for brief happiness. You do not need to set yourself on fire to keep others warm (that's one of my favorite quotes that a friend told me when I was going through a similar situation). You deserve better, and can find it. He seems like he needs to sort out his life first and is emotionally abusing you, even though you may never want to label it as such. Not to be condescending, but my experience with people in these situations is most never leave no matter how much advice is offered to them. I would suggest leaving, but I believe you are not going to do so and that's your decision.
You can find someone who is amazing and happy for more than a a few sporadic moments and they will not manipulate you or treat you as an emotional punching bag. Do what is best for you and your own happiness, yes leaving him will have the cons of missing his up days, but there is whole world of things you will gain as well.
I have been in a situation similair to this one the guy is actually still my best friend today but he seemed to use me as a back up plan. He would date me only if he couldn't find anyone else at one point. I know how hard it is to move on and even though I have a bf now I still have some feelings for my best friend. I sayas hard as it is to move on to try it. Find things to do to keep your mind off him and maybe get a few friends to set you up on dates. I am sure you can and will find a better guy.