As my wife is a nurse, she has had an antibody blood test to check for covid, and it has come back positive to say she has had it. what are the chances that i will also have had it? we have not been separate at any point.

COVID ABY Test: Assuming test is accurate would think you also had it. Was either ill in the last few months with something that might have been COVID-10. As you know the "illness" can be very minor. But even those who have silent COVDI-19 can be sSee if you can also get the ABY test. We are still learning the reliability of the many tests. I would keep looking at CDC.gov every few days to see what is new.

Likely exposed: It is almost certain that you were exposed to the virus. The possibilities include: you did not get infected, you got an symptomatic infection, if latter, you may or may not make detectable antibody to the virus. You may get tested for antibody, but there will be nothing to do with the results. Wish you good health!