My balls are irish (mars and jupiter)

Happy St. Paddy's Day everyone.

I feel like kicking some arse today, so don't tempt me. My ex-girlfriend invited me out to this english pub, the black horse, in condesa, but I'm realizing now that she didn't actually invite me, I invited her to invite me. Last weekend her and I were talking;

me: I'd like to go out for St. Paddy's Day
her: Sure, it could be like for your birthday
me: as long as we don't say so. Are people going to the Black Horse?
her: no
me: well, do you wanna do something then?
her: sure

Then yesterday she simultaneously tells me that she made other plans with people and that they're going to The Black Horse. So I'm like: why, we already made plans I thought (kind of like last week when she ditched out on me to go dancing... she doesn't even dance.) After lots of pausing and consideration she invited me to go "when we figure out what we're doing" and I accepted like a big moron. How can I be so stupid?! Why do I even bother... Get it into your thick skull, Tim: SHE DOESN'T WANT TO GO OUT WITH YOU.

Now I have to tell her that I'm not going to go (if she calls), but I can't say it's because she intentionally flaked out on me and only invited me cuz she felt like she had to. She'd never admit to it (who would?) and I'd just look like I'm feeling sorry for myself, which I am. I can't say that I don't want to share her with a bunch of drunken brits either and that I'll happily knock the piss out of the first one who sticks his tongue in her ear (which will take about an hour, more or less, I'm guessing). Too scary. I can't say it's because i want her all to myself. Too possessive. So what do I say? I'll say that it's because I want to be by myself, which is at least partially true... and that it has nothing to do with her. That's a lie we can both live with.