@RisingToShine,
I find it odd that at 4AM on the night in question she was thinking of him.
Almost every 'texting' social person has a new years eve with family and friends.
You have a bit of an issue to deal with here, because either she was indeed with him for a certain length of time, or she has probably gotten drunk and did not truly see him as a gone part of her life.
From this I would extrapolate that the probability is high, that whether he has cheated or not, it is likely to happen.. Especially given he will not ensure you are there or he is with you at the time the bell strikes... New years eve would not be the same without all who you intend to be with for the following year in the event. In your circle as put forward at very least, since, even the EX saw it as ..at very least, an important night with regards boyfriends... Which suggests, he chose family and knew it was important to women, 'who was where'.
You will have to find out who she was with that night, to ascertain if he preferred to be with her at the midnight chimes, I would think.
Perplexing and irritating, I myself prefer to avoid any indication of all this.. Half truth's, if you prove any, should certainly prompt your action to master the situation yourself and take decisive action. (Look at the obvious friend lie).
Can you not find a man who does less milling around and has more respect, with regards absolute clarity and comprehension of pain?.
All that said, some women are a bit as that, but what are the chances that only one text would be sent?.. Surely a women attempting to drive a wedge has been at this more?. Does he delete the messages and does he read them and react oddly?, IE: going away or breaking commitments regularly?.
The only possible reason which alleviates this, if she has not lied, is that he feels sorry for a girl alone entirely, when you are not.
Best wishes.
D.