I'm so sorry you're facing this.
Answering your questions:
Have any of you been able to talk your spouse out of a divorce? Before I divorced my first h., he threatened divorce a few times, and I put it off by basically accepting all his demands for freedom to cat around with whoever he wanted, spend our scarce resources on stupid stuff while the lights were getting turned off on me and my babies, and treat me like some sort of friend with benefits.
If you initiated a divorce, do you have any regrets? Finally, I'd had enough, and realized that the main thing I felt when he walked out the door each day was RELIEF! I divorced him, and have never had any regrets, even about him being 'missing' from the kids lives, because guess what? He was ALREADY GONE emotionally, and he could have spent lots of time with them afterwards, but he didn't, because he was too self-centered. I grieved, but I never regretted.
What are some of the downfalls of going it alone? Honestly, for me, being alone was easier than being married to the king of dysfunction. I had to be the sole breadwinner, and money was tight, but my expenses were under my control, my kids were my world, my home was my castle, and I finally got a dog and a cat, which the kids and I had always wanted, but my ex had always whined about because they can be messy. Living alone I was able to realize that I was not, in fact, the whiny, clingy, pathetic, insecure, unbalanced b*tch that he accused me of being, but that I was instead smarter, stronger, and able to get things done for my family. I got my sense of humor back. I'm not saying it was easy, or that I never made mistakes along the way, but it was the best thing I could have done under the circumstances, and it made me strong.
Also, it wasn't forever...I divorced when my kids were 5 and 4, and remarried to a wonderful, considerate, and committed guy when they were 10 and 11.
Ask yourself why you want to stay in this relationship. Is it more because you love him and he is worth loving, and you know he loves you? Do you honestly see things getting better eventually? Or is it because you fear the changes that would come your way? Being afraid is very understandable, but I want to give you encouragement that a better future is possible. For your kids, this young age is an easier time to divorce than when they are 7-12. Do you have any family that you could rely on while you make this transition? If you don't see things getting better, it might be time to start thinking about your next steps to get out of this marriage.
Sending my heartfelt condolences and strength your way.