Just yesterday I and others were noting the friendly attitude of all forum members. I think that still holds. The person who attacked you did not do it in this forum (unfortunately, that could still happen). As pointed out, anyone with a connection to the net can make their thoughts known. The bad along with the good.
Peter, I am in a profession where it is expected that people will express their belief that I have questionable parentage, have no job knowledge, no compassion, prefer to do things that are designed to anger people, and don't wash my feet. So I guess it is easier for me to say, but I will say it. Don't let someone like that get you down. You must be and I am sure you are, above people like that. You know it isn't a perfect world. If you don't run up against the imperfections often, good for you!
But when you do have the misfortune to encounter one like that, realize that you have been accosted by an imbecilic moron without moral courage. Do you think the person was correct in their assessment of your abilities? I hope not. Consider then, why let them get you down? If they are correct in some of their assessments, it is no news to you. Ignore the vile the critique was delivered in, you don't need it to store the knowledge you already have.
And while I am at it, add me to the list of those here who admire your work. In the unlikely event you do lack confidence in your work, get over it! If you think you have room to improve, get in line. We all do. I certainly do!
Lastly, why do you think the person attacked you the way he did? Was the person looking for a reaction like you gave him? Do you want him to win that way? Do you think you are the only person in the world this person attacks? I can tell you from experience, that is unlikely unless it is someone closer to you than you think, that has taken a dislike to you.
Only you can decide how you should react to this. Maybe I am just too bull headed, but I wouldn't let someone get to me, or at least allow him to see that he had gotten to me so easily. As long as that type of person sees they can affect you, you will hear from them often. When they see they can't, most don't enjoy continueing if they can't see effects. I would suggest you don't give him any victories. I would also request you don't deprive us here of the chance to admire and learn from your photography.
Whatever you decide I know I, and I think all regulars of this forum, are with you.