Hey OP. I've been following your threads since the beginning, and hope you don't mind me joining.
I was in a similar position to you once. No children involved, and my behaviour wasn't as extreme as yours (apologies if that is harsh) - but I was checking up on my fiancé, asking him to be home at certain times, questioning him etc. No social media in those days, but I'm sure I would have been on that too. I was so desperate to stay in the relationship, even though it was breaking me, and we weren't happy. My friends and family gave similar advice to what you have received on your posts.
One thing I failed to see, was how much he was starting to hate me, truly despise me, because of my behaviour. Yes he had the OW, but everytime I asked him about her, about where he had been, whenever I tried to assert myself and let her know I was still there and not going anywhere - it drove him more to her. He still slept with me, would still give me hope that our wedding would still go ahead, but ultimately the minute OW was free, he would have been off like a shot. He stayed with me for convenience. I didn't realise until after, how pitiful and pathetic people thought I was.
I truly wish you luck, and that one day you may be free from your situation. I think it is clear what your DH thinks of you. Your behaviour is not healthy, nor is it acceptable, to either of you. He will never let her go, and your obsession with her number will never stop whilst you're with him. Ideally you'll hold your head up and leave, for your sake and for your children. They may be young enough currently, but one day they will understand. They will know their parents despise one another, and neither of you will realise the effect on them. It is so much easier than done, for strangers to say this on the Internet, I get that, honestly. I hope you will see your worth, that you are much more than this, and that your life doesn't have to be this way.