I completely empathise. In my lowest points, I've contemplated taking a loan out just so I can put my baby into childcare a few days a week so I can get time to myself.
The thing is I'm blessed by good sleeping children, a husband who gives me lie ins and takes them out together far more than I do for him to give me time to myself and two sets of involved grandparents yet I still just feel I'm wishing my life away.
I don't regret them and wouldn't want to be without them as I've always wanted a family but Christ, I just feel myself wishing time away. I do feel almost certain I will leave my husband in a few years just to make myself happier and be a better mother to my children.
And also to provide some consolation to one and done parents. I've read some comments that friends can never be like siblings or family. Well let me tell you this. I have two siblings, one who is a twin yet my best friend is MORE like family to me and my kids than my siblings ever will be.