Stung, I feel your pain. BTDT alone for the past 14 years with three babies who have grown in to teens/young adults. It is exhausting and overwhelming. When they were tiny, I had to learn to let a lot of things go (house just wasn't going to be spotless all the time, meals had to be kept simple, the girls' hair and outfits didn't have to perfect, etc.) I still got stressed way too much, and I now have serious regrets about not just living in the moment with them more often. I wish I would have said 'yes' to them more often, and just played and had more fun with them. I was so enmeshed in running the show, trying to hold everything together, that I checked out of the fun department for too long. Makes me sad to think about it now. Really sad, actually. Too much control on my part.
You do need 'you' time! Guilt-free 'you' time. You've been dealt an involuntary hand of single parenthood. You've shifted gears into running the show single-handedly, and I think maybe your brain is having a hard time entertaining the idea that it's okay to give up control and enjoy yourself. After all parenthood is about sacrifice, especially when you do it alone. But, girl, if you don't allow yourself to have some fun and treat yourself to something, you really aren't doing your kids any favors. Those babies need mom to be happy and as stress-free as possible. Some chill time does the soul good. Take care of you.