Ahhh, sweetie. I'm really sorry for all you have been through and all you are going through. That two week appointment can't get here soon enough. I do think our mind will naturally picture worst case scenario. I don't know a way to make that not happen. All I can offer is to stay as busy as you can, ask for help with your support system, and be kind to yourself. Come back and tell us how you are doing!
Some people worry, some worry a lot, some a little, some not at all. That's not the same as anxiety. Often in our society today we have turned grief into a medical problem. Only time can handle grief. Therapy can help, friends can help, moving on can help. My father was widowed twice, and left his third wife a widow. That was her second time, and, like my Dad, she suffered for awhile and then got married a third time. They were both good at suffering and then moving on. I have an anxiety problem, and it's an entirely different can of worms. Becoming a widow while pregnant presents anyone with problems, as does becoming one while having kids -- not just the loss but the financial difficulties. It affects everyone in a bad way. That's also not anxiety. If you hold on to grief too long, it presents a problem and can then lead to depression, which can lead to anxiety, but usually in people prone to it anyway. Because you mention the widow part along with your anxiety, I'm assuming you attribute one to the other, but that's not necessarily the case. It does show that if this is still bothering you after three years, you're a worrier, and thus you're worrying about cancer. Since cancer is going to do what's it's going to do and your job is to do what you can to deal with that as would be anyone's problem, worrying about it only makes it worse, so the problem you can work on is why you worry so much, or more importantly, how to limit it. Techniques such as meditation, staying busy, having a passion in life, and plain old moving on can be learned. If you do have a real anxiety problem that isn't grief, that makes learning these things harder but if you do learn them the anxiety too will be something you've learned to limit. Life always punches everyone eventually, but our personalities determine how we take the punch. How much we're isolated is part of that aspect of personality. That you can work on; whether you have cancer or not you can't.