I'd certainly be willing to say that the US spends far, far too much money in general, too, though. Very inefficiently to boot. But I'd say that foreign aid is probably the least of those inefficiencies... much of our wasted money is in the social programs the OP says we need to dump more cash into, imo.
That and defense. Especially defense. Hell, we spend more on a single one of those fancy-ass, totally useless and mostly broken, brand new F-35 Raptors than we do on foreign aid entirely. Instead of dropping foreign aid, how about we stop spending several hundred billion dollars on a broken-ass plane?