You might want to consult a couple more Agents on the market value of your home. Most of the estimates should be in the same ballpark.
It could be that your friend is being more honest with you about the value of your home and the other agent gave you a higher number because they already knew you expected it. This is called “Buying a Listing” and is something a lot of agents do to get you to sign with them. When they have your property on their portfolio for awhile they will then suggest lower the price.