I'm with Lisa Fridebourg-Lloyd on this one, & so I invite you all too to do the same and make up for hurting another soul. 

People underestimate the power of an apology but also the power of pain, it can really ruin a person or make them sad and angry. You'd be wrong if you said pain didn't change a person, and when it's pain that's unnecessary & callous, it's only really change for the worst. 

But it's never to late for a sincere apology, if the sting is in your heart and no doubt there's, suck out the poison. If they don't forgive you at least you've made amends & helped them and you in some way & when they're ready they'll come back & if not both of you've learned something. 

Just don't let the pain you're aware of causing continue. That's just not right & not fair on the other person, you're better than this.