@Megadivamama
I feel if the decision was somewhat more mutual it would be alot easier to raise, implement and follow through
But as you know, it's always going to have to be a unilateral decision on your part! and it's never going to be easy. You're right to recognise how painful and exhausting it will be. That doesn't mean it's not worth doing, or that you won't find the resources within yourself to get through it somehow.
I know the grass isn't always greener on the other side.
Hang on, though, I kind of think it is. Regardless of whether you "find someone better" one day (although you probably will; or at least have fun trying!). Because there is nothing worse than dying of boredom. Imagine yourself in 30, 40 years' time, sitting on the sofa with him. What would you advise yourself now, if you could travel back in time?
I'll let you into a secret: The "someone better" you find is yourself. You learn and grow in ways that would never have been possible if you'd stayed together.
Keep observing how you feel from moment to moment and just make a note of how often you feel happy / bored / irritated.
It might help you to read Daphne Rose Kingma's "Coming Apart" -- I often recommend it on MN threads! I promise my name is not Daphne Rose Kingma!!!!!! but this book helped me enormously, and has helped friends too. There are some exercises at the back that are really worth doing. It helps you to understand what's really going on when it feels as though you're just trying to destroy everything: it's actually a positive, healthy process... just, erm, not much of a fun one. But it really helps to understand why it's happening.
The book might also, in your specific situation, help you to prepare... e.g. for the inevitable feelings that you can't bear to be without each other, are making a terrible mistake, etc etc etc. This is all a natural part of the process, unfortunately, but forewarned is forearmed! If you're lucky, you might even be able to work through the exercises together at some point.