The usage of your images should have been VERY clear.
Surely this would have been pointed out by the first shooter at the time? Why would he let him come to some wedding as a second shooter, learn from the guy.... and at the end of the night walk away and then sell the images backdoor stlye? I know the OP has explained it a little better now, but from the first post, it sounded a bit suss.
This was why I asked how the bride got in touch with him thinking the OP had a quiet word and threw her a mobile number. But I stand corrected as it was explained.
If I ever got the chance to do this with a pro, I would be EXPECTING to hand over all the RAWS and not sell them to the bride on my own. It's his gig, his business. If he calls me back for another wedding because I did a half decent job, THEN we start talking compensation..... Or is that just me being a little naive?
My current job and one I have done for 30 years now I worked for a week as a pimply kid for free to simply show the guy I was keen. He put me on as an aprrentice and the rest is history. Sometimes it's better to look longterm rather than short term. Btw, after the week was up he did pay me for that even though I said I would work for free.