Pof well, from the outside, it looks like you caught him out, he's managed to wriggle out of it by feeding you a line (sorry) but of course it's changed things. You quite rightly don't really trust him and on his part I would imagine there is guilt and embarrassment, plus whatever motivated him to go back on the dating site won't have miraculously disappeared.
I would tread very, very carefully here, protect yourself emotionally as much as you can as this kind of thing gives me a very bad feeling. On the other hand, I've been in a similar situation myself, which didn't end well, so maybe I'm just a bit cynical and jaded.
I'd be tempted to leave it with the texts and see what happens. Have you actually booked somewhere for this weekend?
Life is really too short to waste time with someone who blows hot and cold like this. I don't know if you remember me at all, but last year when I started dating I had a six/seven month relationship with a bloke who was like this and I suffered from horrible anxiety with not knowing where I stood despite him saying he loved me and making plans for the future. (And yes, it was this man I found back on the dating site ho hum). We split up when I told him I wasn't prepared to put up with it any more and I learned a huge lesson not to put up with the crumbs from any man's table ever again.
The big question is whether this man and your relationship make you happy.