If it helps one of my closest friends went through this with her now ex of 5 years, and spent months deliberating and agonising on what to do, and ended up ending the relationship. Ending that relationship was 100% the best decision for her. She spent a year or two loving and enjoying being single and having fun dating, and recently moved in with her new boyfriend who is a much, much better match for her.
It’s definitely not a decision she made lightly and you shouldn’t either, but there’s a couple of things you’ve mentioned here that she felt too/something similar to.
It’s okay to grow apart from someone and it’s okay to want something different/better/new for yourself. Putting yourself and your wants, needs and feelings first doesn’t make you a bad person