Background:
Beth and I had been going out for a year and a half. We had one day breakup 8 months in and then a 3 day break up a year in. During the one year breakup, there was this girl Dawn who I was friends with who I seemed to have alot of chemistry with, but although there were some close calls, nothing ever happened. Dawn moves away, during a blowout fight in April I let it slip that yes, Dawn was a possible threat during that 3 day breakup because she kept badgering me about it.

Now:
Beth asked me to go to Belmont Stakes months ago, and I was weary because I don't like her friend and I barely knew it was a horse race.
After a botched attempt to connect with her friends Memorial Day weekend, I asked to go but Beth said tickets to her section were sold out.
On Thursday I got a text from a girl Beth is supremely jealous of (Dawn) saying she'd be in town that weekend.
Out of respect for Beth, I immediately informed Beth of her arrival and offered that she hang out with us, so she's not all nervous.
Beth immediately assumes I rescinded on the Belmont Stakes offer in order to hang out with Dawn, though I did have a vague notion she would be visiting in June, I had no idea when.
I assure Beth I didnt, I even show her the text from Dawn confirming the dates that morning, and I agree to go back to Beth's on saturday so she knows where I'm sleeping.
I go to this party, Dawn doesn't even show up, so I'm like Beth will be happy with this, and I show up at 3am at Beth's.

We get into a huge fight, I leave.
Sunday morning I get an email saying she thinks im sketchy, and all her friends thinks im lying, and that I don't care what she thinks.
So I call her and we fight and I say I can't care what she thinks if she thinks I've been conspiring for 2 months to cheat on her.
I say after 1.5 years and there's no trust we should end it. We do.

I immediately send an email saying I told her the 100% truth the whole time, I've accommodated all of her requests, and it's never good enough.
And truth be told, I have never cheated on Beth, and was not planning to last weekend.

So next move?

Beth told a friend of mine she thinks I'm lying about Belmont Stakes on Monday, so my explanation is nullified.
Also, I could be expecting a call from Beth explaining what a big stupid mistake she's made and she's sorry and she'll work on her trust issues etc,
however, if she thinks I have cheated on her on Saturday (or was going to), she probably already thinks I've slept with her by now (wed) as Dawn's here all week.

I'm not interested in reconciling, really, but I'm in no moral obligation to communicate any further?
I've said my piece, she doesn't believe me, I didn't do anything, so she's crazy.

...Right?