Tbh your OP makes you sound as if you're depressed, understandably.
I lived for many years lonely in my marriage and I suffered with depression for a good deal of that time because it's soul destroying.
Eventually I told him I couldn't live with him any more. It was the best thing I could have done.
I won't say it was easy, certainly not at first.
He was quite controlling. He controlled all our finances and I was a SAHM. Suddenly I found myself having to deal with everything on my own. Trust me, it's easier than you think.
I didn't date for many years, not because of the children but because I just didn't want to, and that was fine for me. I got myself a job and made a life for myself and my children that worked for us.
Your children will know that you're unhappy and will pick up on the unhappy relationship you have with your husband. They might very well be happier out of that strained situation.
I can't imagine that your husband is happy either, but that's not for you to worry about. He's an adult, he can make his own way in the world. You need to concern yourself with you and your children.
Leaving the children aside, being on your own does not have to be the same as being lonely.
Feeling alone whilst in, what should, be a loving relationship is being very lonely.