just an impulsive, excitable fool sometimes.
No, he's manipulative and self centered. If you believe what he told you about why he applied for a job without telling you, you need to give your head a wobble. He had this planned. He knew you would object so he didn't tell you until it was nailed down. This does not bode well for the future of your relationship.
Don't do it.
Yes, you could get a fiance visa - it takes about 9 months, and now that USCIS is building a backlog, it will take longer to process this application, so maybe in 12 months you could get the OK to travel. You could get married within three months of arrival in the US, if you can find a courthouse open in the state where you live, or DC, assuming the virus is still active and/ or a second wave is ravaging the country. You could forgo the UK wedding of your dreams and then apply for a spouse visa. Same time frame though.
Either way, you are looking at a medical exam including a chest x-ray, and lots of paperwork. Can your company work with that sort of delay? Do you know if your company is covid proof?
He is a citizen, you would get a Green Card, eventually. You have children together, you bought a house together - you can both answer all the questions USCIS will ask you about your relationship truthfully, to prove that you are not a gold digger looking to falsely enter the US and get a job from which you could be fired without notice and for any reason so you will never know if you can schedule an appointment for a mammogram six weeks ahead if people are talking about layoffs in your office (because your health insurance comes from your employer), living in a small apartment, paying a fortune for childcare, and enjoying exactly one week off per year.
You could get a job, your children could settle into daycare, then start school.
Or Covid 19 could wreck the economy and your family would end up living in a cardboard box on a railway embankment. Or you could come home and look for a job in the UK.
On top of the fact that USCIS is not processing applications right now, nobody knows what will happen to the economy under the double whammy of Trump and the virus.
No matter what, you will miss the UK. You will miss your friends and your family. It will sink in that you are a foreigner in the US and a tourist when you return home.