"IF"s do not belong in apologies.
The only time IF should be in an apology is:
a) if the apology is for a future possible action or outcome:
or b) if you are in crowded place such as a Subway train:
or c) there is some uncertainly as to whether you are the person to blame, or if another person was responsible
Under no circumstance, unless you fancy the idea of someone wanting to harm you, should you add "IF" to an apology when you have just been told that you did something that required an apology.
The phrase "I'm sorry if," when there is no uncertainty, directly translates to : "It is unfortunate I have to hear you bitching right now. I want you to shut up. I am going to say words now in the hope that you will do just that. I am certainly not sorry, and to boot, I think you're stupid."
"THAT" is the keyword to sincere apologies. I'm sorry THAT I made you angry. I'm sorry THAT I got you pregnant. I'm sorry THAT I also got your sister pregnant.
I'm also sorry THAT I rub my crotch on people in the subway.