Idk I never dated and am with my first bf; but I think you should trust your gut feeling,
Plus if he got scared with the exgirl I guess some guys do a ''rubber band effect'' and if he still loves her as he blurted out maybe he is just in his I need to calm down stage.

I wish you the best!
And who knows maybe things misread?

But I say what does your gut or heart tell you???