[Roland]

Welcome to the forum.

For me, it really depends on how live his suit is. If three or more diamonds (apart from “his” diamond) were dead on 3rd, I would probably be willing to cap it. (Or if some diamonds popped up on 4th. The reason is that it is less likely (mathematically; if this guy really knows what he’s doing, he wouldn’t be playing a dead 3-flush, but I don’t think this is a good approach in a .05/.10 game) that he has the flush. If only two diamonds were dead on 3rd, it’s probably best to slow down to so much aggression.
So, assuming diamonds were live, you probably shouldn’t have capped on 5th, and only called on 6th (and the river). At least that’s the way I play it. This assumes your opponent is reasonable though. If you have seen him play aces or aces up this way in the past, you can put in a few more bets.
Playing trips aggressively is good, but they do get beaten once in a while.