You don't say "sorry" unless you mean it. The trick is to FORGIVE them for their misdemeanours. That makes them mad as hops and it gives you a release of emotion that is priceless. That hate, by the way, is hurting YOU and not them. You can't ever be happy if you carry that torment around in your heart.
I've done it! But ONLY for someone ELSES sake who i loved very DEARLY! It's tough! Because the person I apologized to HATES me and I KNOW it. If you need to "suck it up" for someone who means the world to you-then DO IT! Otherwise-well, it starts with the 6th letter of the alpabet, and ends with a "u"
A really good apology I heard recently was "I'm sorry for what I said. I didn't mean it the way it came out. I should have behaved better."
If you're wrong, it's ok to admit it, even if it is to someone you hate because it's not always about the other person. It's about you being able to recognize and learn from your mistakes; and an apology is part of that process. :)