Options:
1. Get a Tier 2 visa yourself from your employer to sponsor you. You will either need to be in a skills shortage position or pass the Resident Labour Market Test proving that your company could not hire a UK National or EU national for the role (that's posted for 28 days). There is also a minimum salary that must be earned depending on your role. Your company will need to hold a sponsorship license to go this route.
2. Once you are divorced, you can marry your new partner. You'll have to do the long distance thing and be in the USA while you await the divorce and marry and reapply, which will likely time some time.
Your estranged husband is required to notify the Home Office that the relationship has broken down and you'll likely be issued a curtailment of leave letter after that happens. I think you have 60 days to leave or get a new visa, if I recall correctly.
Best of luck, I hope it all works out for you.
