It's such a crappy time @DomThom. The worst bit, the absolute pits. If it is cancer, once you know what you're dealing with and the doctors form your treatment plan, it'll get easier in a weird kind of way.
In the meantime try to stay in the moment as much as you can. And distract yourself as best as you can. It's so easy to say, but try not to cross any bridges until you get to them.
You're right, reassurance isn't really possible, but know this, whatever happens you'll get through the next month, the next six months, the next year. You're stronger than you think and so are your kids. My experience of BC has brought me closer to my husband and my friends. I've felt more love than I ever knew possible. My kids have shown resilience and compassion, and I think it will make them more empathetic people.
I'm sorry you find yourself here, and I sincerely hope that tomorrow you're not. But if you are diagnosed, we've got you. Deep breaths, K xox