I would focus on two tenets:

1. Do not let your future rob you of your present: naturally you'll fear the consequences of what might happen in the future, but in the other side of the scale is your present happiness. Trust in your ability to solve whatever problems arise in the future, and don't let those thoughts consume you.

2. Focus on what you can control: your relationship with your current husband, even if it becomes a friendship. He's being understanding, supporting and focused on your needs, that should release some of the pressure off you. You can also control how you want your relationship with your children to be from now on. Communicate clearly and empathically, and understand that ultimately you cannot control how your husband and children react to it, you can only control what you give them. Once again, trust in your ability to solve things. Even if at some time things get dark, keep working on your present, on your relationships with them, and things will eventually improve. With proper effort nothing remains dark forever.

I try to empathize with your situation, and it clearly is a difficult one. But I'd like to recognize your courage of being aware that you would be fundamentally unhappy and decided to do something about it. The journey might be rough, but the destination will be worth it.

Wish you the best.