Is how Daemon [spoilers] his wife even possible?

It's the first ('horse') step of the kill that bugs me: Daemon advances (with no weapons in hand) toward Rhea and her horse; Rhea reaches for her arrows & bow (I think) and her horse (perhaps sensing her sensing danger) rears up. Rather than getting trampled by the hooves of Rhea's horse Daemon somewhat amazingly gets in between the flashing hooves and pushes on the horse's chest hard enough to make it fall backwards, i.e. to go all the way over onto its back crushing Rhea. But is this really possible? Big horses of a racehorse-ish size and quality weigh a heck of a lot, hence they can crush their riders, but then I wonder how Daemon can impart enough force in just a fraction of a second to push such a (defending itself) horse over backwards?

At the very least this whole first step of the kill seems to me like a fairly miraculous piece of improvisation by Daemon. Realistically he couldn't know for sure that (a) the horse would rear up at all, (b) that he'd be able to avoid the horse's hooves and serious injury himself, and (c) that he'd be able to hit the horse just right and with enough force to completely flip the horse over and thereby do the necessary maximal amount of damage to Rhea. So I guess we're supposed to think that Daemon just improvised what actually happened, and that he was just spectacularly lucky with how it all worked out. (Of course he also seems to have been somewhat lucky that Rhea was unaccompanied.) In sum the first part of Daemon's killing of his wife seems to me to be both poorly written and poorly staged and shot (it took me several rewindings and pausings to figure out what was supposed to have gone on; in real time and at full speed the sequence was a "Huh? What happened? 'Is this magic?' moment).