One of the first lessons we learn as children is to always mind our manners.
These always included saying "please" and "thank you," "excuse me," apologizing whenever we did something wrong to someone, and that the correct response to every apology was always "it's okay." Yes, we should always mind our manners, but what happens when someone really hurts you? Does a simple "I'm sorry" instantly make everything okay?
Not every "I'm sorry" deserves an "it's okay" - and that's okay. Sometimes other people hurt us in ways that two simple words just can't make up for. It isn't selfish or overly dramatic to not forgive someone simply because they said "I'm sorry." It is okay for what someone else did to you to not be okay with you. Someone else does not get to decide whether or not (or to what extent) their actions or words hurt you.
Some offenses require more than just a kind exchange of words and recognition that a mistake was made; they require an actual change in behavior or actions. I'm not saying that when someone accidentally bumps into you at the mall that they should apologize and remain indebted to you for life. However, I am saying that if someone you respect does or says something disrespectful to you or someone close to you, you have a right to not accept their apology.
Sometimes we reluctantly accept others' apologies just because we don't want to lose their friendship or because it's easier than putting up a fight, but that doesn't really fix anything. It's a bad habit that takes some serious soul searching to fix, but that doesn't mean it's impossible. Even the most forgiving people have their boundaries.
The next time somebody really hurts you, remember that it is okay to be upset with them and to not automatically forgive them after they just say they're sorry. You're worth more than two small words; make sure they're accompanied by a change.