How come your husband doesn't know anything if you are spending hours each day googling? You should talk to him definitely, it can only help you.
Anyway, it is probably not genetic, but it is learned. Most anxieties come from early childhood, so when you grow up in house where one of your parents has HA, there is greater chance you will develop it.
As for colon cancer, you are waaay to young for that so my guess is you are perfectly healthy. On the other hand, I know the fear, when you don't feel like doing anything because, what's the point, you are going to die soon. Or you just can't enjoy what is happening around you. I can't help you with that since I am fighting the same battle myself. What I can do is tell you what my therapist recommended me to do, and that is to fill my day with different activities, that don't require much thinking, and that can distract me from focusing way too much on my body. Also, harder thing, but also very helpful would be to stop googling completely. You have OCD since you describe googling as an impulse you can't stop. One way to try to stop is to start small, for the next hour, no google, or 30minutes...Then next day try it for longer period of time. You will feel a lot more anxious in the beginning, but my guess is that anxiety would diminish eventually.