CRITICISED FOR ASKING FOR MY DUE

Hi RTers, my name is Kess, i am a public inspirational speaker based in Lagos. About 3 months ago I was given a deal by a neighbour friend (Tayo) to give an inspirational speech to a certain group of people he was mentoring. I was priced real low and agreed based on the fact that we are friends kinda. Normally, I won't take less than N50,000 for an hour speech, but took N20,000 for a 2-hour plus speech because of him. Funny thing was that he only gave me N10,000 and promised to give the rest after the event.

After the event, one of the participants approached me seemingly very impressed with my speech and invited me for a bigger invent a week later. Of course I told him my actual price (N50,000 per hour) which he agreed to. I actually spoke for over 2 hours during the event and was paid in full.

The issue now is that, Tayo heard of the deal and has refused to pay me the balance N10,000. To make matters worse he goes about telling people that i am very greedy because I asked for my balance money; his point being that it was through his link that gave me the other deal, so I should have written off the balance. 

Dear RTers, have I really done anything wrong by asking for the balance of this deal I practically slaved for? Should I go ahead a fight for my balance or apologise and write it off? I don't want a strained relationship with Tayo but don't like to be cheated either.