I'm so sorry you have all this to deal with, OP. It's really tough that your husband is working away at the moment. Do you have friends or family nearby who can help you with the children?
I'm another ovarian cancer survivor - diagnosed about 2.5 years ago after a fall in which I broke 6 ribs - they only picked it up because they were doing various scans to see what else I had done to myself, so I feel very lucky that it was caught relatively early. I had a radical hysterectomy followed by chemotherapy. It was a pretty gruelling time, but I'm currently clear (touch wood).
Someone further upthread suggested you get in touch with your local Maggie's centre, and that's a really good idea - even if it's not that close, they offer quite a lot of online and phone help too. https://www.maggies.org/our-centres/
One thing I'd say is, ask everyone medical that you talk to about what support is available, and explain to them that you have diagnosed anxiety. There is a lot of help available, but you have to make it plain that you need it. I guess some people prefer the stiff upper lip, but I definitely don't!
I don't know if anyone's talked you through the blood tests etc, but they will be looking at the level of something called CA-125 in your blood as it's a marker for ovarian cancer. Some women have incredibly high levels at diagnosis, up in the thousands; others much lower - mine never went much over 100, and the last time it was tested (about a month ago) it was 6.
Good luck for Tuesday. If the diagnosis is cancer, then you will be looked after. Sending you a hug.