Were those two years really "wasted"? Did you not do anything else worthwhile during those two years? Do you value your life so precariously that one thing gone wrong means you "wasted" it? How long do you think a relationship "should" last in order for it not to have been a "waste"? I did read your entire post and although some unhappy shit took place, I didn't see anything that was especially unusual to the point where I would consider two years of my life "wasted" - although I realize that when it's not YOU (me) it's happening to, it's a lot easier to just brush it off as "water under the bridge" or something like that. However, you weren't being abused (were you? you didn't say so), you didn't invest a ton of money in some kind of venture with these people (such as starting a business), you didn't tear yourself apart with self-destructive behaviour, or anything else that would impose severe, long-term repercussions, so I don't see how "wasted two years of my life" applies to this. It's just one of those things that didn't work out. They say that NRE lasts anywhere from 6 months up to 2 years, so maybe this relationship was coasting on NRE and finally ran its course. Also, 2 years is not a very long time to figure out if something is right for someone(s).
As for being friends, don't decide that right now. I have seen other people give advice on here that says to take some time apart and THEN re-connect and figure out if "just friends" is a viable thing.