I guess in my case there has been no "deal breaker" type of behavior(cheating, abuse, etc) which is making me question myself. It feels silly to leave a generally good relationship (which would no doubt effect our children) just because i dont feel happy. But then i switch between thinking, 'well don't i deserve to be happy?', and that maybe this is as happy as i would be with anyone 
May i ask you, has your separation helped you at all?
In my situation there was some mental abuse happening so the separation had to happen and tbh it should have happened a lot sooner.
The thing is (and I know this gets said a lot here) but he is genuinely a good guy who had a horrible upbringing and I think didn't know any better.
He's the husband that all my friends wished they had, does he's share, if not more, around the house, involved with the kids, not controlling financially or in any other way etc etc but due to our history I just couldn't move forward treading on eggshells.
The separation has helped a little, we needed the space for the above reasons but I'm still not sure of my final decision.
I think he is the only one to love me like I want to be loved and know with him getting help we can be great again but it's a bit too little too late for me.
I worry about being alone if I decide to split permanently and I worry about not being 100% happy if I stay with him.
If you were my friend asking me I'd tell you to do what makes you happy. I think if you're questioning that with your DH then maybe it is time for you to leave and find that happiness but I fully understand how hard that decision is, I'm always thinking what if it's the wrong decision and I've hurt people in the process?
I do know though that kids are very resilient, the will cope with whatever decision you make.
My DH has been gone for a month now and my kids are fine. They miss him but they also see him very regularly and we're getting along better when we do see each other as we're not in each other's face all the time.
I'm not sure how old you are (I'm 35 and have been married for 15yrs) and I just know I don't want to get to my 40's still asking myself the same question.