Sorry you and your husband are going through this. I could try and explain what's happened, but you haven't given enough information, which means I'd be guessing parts of it, and that could mislead you if I guess wrongly.
Could you give the dates of the PSA tests, and the dates of the visits to the urologist and the GP. The reason is that it's important to understand the length of time between the PSA tests, and assuming the urologist did a Digital Rectal Exam (DRE), exactly when this was relative to the two PSA tests. Also, was he given any antibiotics for a urine infection, and if so, exactly when that was. I'm guessing (which I don't like doing) that the urologist based the probability of Prostate Cancer (PCa) on the DRE. It might be that the rise in PSA was also a factor, but depending on the order things happened, that could have been caused by the DRE or the infection. A change in PSA over time is much more significant than the absolute values when they're down at these levels, and it's not simply a case of a normal reading means no PCa, and a higher than normal reading means PCa - too many other things cause changes in PSA.
The MRI and the biopsy will confirm or not if PCa is present, and what happened before those will become less significant at that point, but if you can give the extra detail I requested, we can try and explain better what happened so far and what each stage means.
It's useful to put the chronological list of events with dates into your profile, so people can find it when trying to answer questions.
You will get excellent support here, and of course we're all wishing that the tests show no PCa.