I'm going to abandon my friend of 7 years
Why would you abandon your friend of 7 years?
He was so old and boring to me, I don't need him anymore.
Friends can drift apart over time, but you shouldn't be ending a friendship so suddenly.  At least tell the friend if something is wrong, and maybe you can work it out together.
Nah. I'm going to cheat on him with his lover and tell him off.
What you are doing is inconsiderate here. Breaking up his relationship is needlessly harmful, since he has done nothing to you.