Opinions on my relationship

Sorry for the long essay incoming, I talk a lot and there's no way around it. I have this problem where I always second guess and doubt myself, accuse myself of being crazy, overreacting, etc., so I'm looking for anonymous opinions on my relationship stance.

I've been dating my current boyfriend for almost two years but I've struggled with the thoughts of breaking up for months. He's not a bad guy, but there are many reasons I have, mostly concerning the future, out different wants and needs. He's perfectly content but I want more that I'm not getting from him (and asking would be too much, as proven in the past). And yes, I have communicated with him about my wants and needs but they either go ignored or end in an argument. Either way, I'm unhappy, though I gave up fighting for what I wanted and just settled. Now I'm kind of apathetic. He's a good companion and friend, but I am no longer feeling tan emotional connection. My heart isn't in it.

Recently, my old friend contacted me to say hi and we got to talking. We had crushes in each other back in the day, and he wanted to pursue it but I shot him down (I won't go into detail, but I did it for his own good. I didn't feel like he was ready at that moment) and then we ended up going our seperate ways.

When my friend and I started talking again, it's like everything picked up where we left off. He said he's talked to me about things he can't talk with most people, and I've definitely shared with him some of my darkest secrets that I haven't told anybody else. Some secrets, in fact, my boyfriend would probably judge or shun me for.... My friend, on the other hand, we know rachothers bad qualities, know the worst of the other... I always had felt a deep emotional connection with him and even though I had turned him down all those years ago, he was still always an amazing guy, and content being my friend. Even when I was bad at replying, he's always been awesome and supporting.

So, I'm torn. I asked my friend to leave me alone for a while so I can sort my shit out. And no, we weren't having any "explicit" convos, I wasn't cheating. I simply told him I have feelings for him but am in a relationship, so let's distance ourselves for a while. And he understood. The fact that strong feelings came back for my friend is probably a testament that my relationship is over, and should have been over a long time ago. I've just been too pussy to break up all this time, but to be fair to my boyfriend and not waste his time, I think it's something I have to do.

But that scares me. I'm terrified to have that conversation for the best. I already was unsure in my relationship, but if my friend never came back into my life, would I have wanted to end it so soon, still? Am I just looking at my friend, with "the grass is greener on the other side" mentality?

How can I know for sure what I'm feeling, when I don't feel sure of anything anymore...

Sorry for coming off as whiny. I think it's apparent I need to break up with my boyfriend, but what if that's a mIstake?