Personally, I would not boil or process them, boiling them will set the pectins and give you some nice strawberry jam. I would throw them in your secondary carboy and rack your mead on top of them. First I would let them thaw out completely, then refreeze them, and thaw out again before adding them to the carboy. This will help break down the cell walls allowing for better extraction of flavors, colors, and sugars. If you are concerned about their sanitation, use campden tablets. Add one or two crushed campden tablets to the strawberries, once they are in your already sanitized carboy. Wait 24 hours and then rack your mead on top of the fruit.