Based on the information you've provided you will probably be fine. As long as she never reported the conversation you will be fine. However, if you want more detailed information you should consult with an attorney.
The odds of anything happening nearly 2 years later are slim. In order to prosecute you for threats, they would have to prove that you said something that conveyed an immediate threat of death or bodily harm to someone, that you intended it to be taken as a threat and that the person was in "sustained fear" for their safety (or the safety of another person). It doesn't sound as though you had that intent.
What I'd strongly suggest is that you stop bringing this up. You've made your peace, she accepted your apology and it sounds as though you can both put this behind you.
The statute of limitations is three years, so it's nearly too late for them to prosecute.
The above answer is for general information only and is based on the information you posted. Every case is fact dependent, so to get a thorough analysis of your situation, you will need to consult face to face with an attorney licensed to practice in the jurisdiction where the incident took place. Do not conclusively rely on any information posted online when deciding what to do about your case.
After two years, based on the facts you have posted, you should have no issues.
The above is general legal and business analysis. It is not "legal advice" but analysis, and different lawyers may analyse this matter differently, especially if there are additional facts not reflected in the question. I am not your attorney until retained by a written retainer agreement signed by both of us. I am only licensed in California. See also avvo.com terms and conditions item 9, incorporated as if it was reprinted here.
I agree with Mr. Dane. You may also want to think about what you say to people in person and even more importantly in chat rooms where there is evidence that be gathered against you. Its a good habit to "think first" before you say anything that others might find upsetting, threatening or controversial. Sounds like this matter is not going any further, but you'd be smart to learn from it.
After two years, it is unlikely anything will happen. Based on your facts, it sounds like there isn't much of a case. To convict someone of a criminal threat, the prosecution must prove that the defendant intended the comment as a threat and that the recipient sustained fear from it. Based on your description, above, it does not appear that this is the case.