The only .32 that I can think of that had an actual frame mounted decocker would be the Sauer 38H, made in Germany from 1938 to 1945. Adopted by the German military it was reliable, durable, and probably accurate enough out to 10 yards, but the mag held only 8 rounds. Today it's definitely best suited for the collector and maybe for the occasional shooter whose interests lie with WW II weaponry.
The Beretta Model 81 and the CZ 83 are both high capacity .32's but lack a decocker, using a manual frame mounted safety to block the hammer and trigger. The Browning BDA 380, which is essentially the Beretta Model 81/84, differs from them in having a slide mounted decocker. The problem here is that while it was made in both .380 and .32, I don't know if the .32 version was ever imported into the U.S. All I could find on the online auction sites was somebody offering a BDA .32 12 round magazine.
Good luck with your hunt.