Wow. I have not been here in awhile. But it feels good to be back

I do have an issue that I'd like other people's opinions on, but first, here's a bit of a background- My partner and I have dated for 3 years, broke up for about a year, then we recently got back together. The relationship wasn't working because we both had personal issues that were creating a lot of tension, and because of the tension, we weren't in an atmosphere that would have helped us with our personal issues. It was a cycle that needed to be broken. After a year of wandering, some personal growth, therapy (that lead me to Psych Central ), more heartbreaks with other people, etc., my ex and I ended up with the same conclusion. We love each other, and we wanted to do what it took to keep each other in our lives.

During our break up, we tried seeing other people. They didn't work out, of course, considering what we really felt. I had my little mishap not long after our break up, so several months has blown by and that mishap is now but a memory. My partner, on the other hand, had a fling not too long ago from now. For the longest time, he refused to date anybody. Finally, he did start a fling that lasted for about 2 weeks, but it was the last push that made him realize that he didn't want anyone else. Unfortunately, the girl he had a fling with isn't so understanding.

To him, the 2 weeks was a fling. To her, it's AS IF SHE dated him for 3 years. She really is acting as if they were engaged at some point but then he left and that he and I ruined her life. And I know this because, in a particular social media, she's been talking about how much her heart has been breaking. That's ok and all, sometimes people just fall harder and faster than others. But the problem isn't there. The problem is that she's also beginning to defame my partner, calling him names, saying that she might be pregnant (they used protection in the ONE time they had intercourse. I asked my partner if the condom broke or anything, he said no because he checked), and now she's at the cusp of even bringing me into the picture. Worse off, she's also friends with a few of our close friends.

My problem here is this- I can be a very angry person. I WANT to retaliate, I WANT to tell her off, to make her back off, to tell her to just get over it. But I know that any kind of acknowledgement is what she's waiting for. She wants me to go all angry and insane about the situation, even if I know better. She wants me to question my relationship, to look at my partner as the villain and her as the victim. She wants to play a game. So, how do I deal with this? How do any of you deal with people who are doing whatever they could to ruin your day? To ruin your relationships because they're angry? Is there a point at which I should retaliate? Or if I should just ignore it, any tips on how I can go on with my renewed and delightful relationship without letting her and her childish rants get the best of me?

SORRY for the long post. And I thank each and everyone of you who takes the time to read it and/or respond to it.