Don't forget that first and foremost, you need to follow instructions of the crew while onboard. If you feel greatly wronged by this, feel free to send an email after the fact to customer care. Going to the captain, etc. isn't the right approach nor is arguing with the FA while onboard the aircraft.

IMO, you need to get over it and move on. By all accounts you were wrong in this instance as your stated laptop does not meet the weight criteria. Continuing to whine and berate the FA on this forum is poor form and does not reflect well.