1y/o dog won’t accept new puppy – need advice!

Hey everyone, I really need some help or reassurance because I’m feeling kinda stressed about this.

I have a 1-year-old Pomeranian who’s always been super vocal on walks — he barks at other dogs and strangers, but he’s never been aggressive. If someone approaches him, he lets them pet him and he’s actually pretty sweet. We’ve always described him as dramatic more than anything else lol.

But… we recently brought home a new Pom puppy (3 months old, like 2–3 lbs) and my older pom (14 lbs) is NOT handling it well. He growls, barks, and even snaps at the puppy totally unprovoked. I’m honestly scared he might bite the puppy if they get too close. We’ve been keeping them separated with a baby gate, but even then they just bark at each other through it.

Another thing that concerns me is that if we try to pull the older dog away while he's barking/snarling, he sometimes growls at us too and even snaps in our direction – which he's NEVER done before.

We tried introducing them on neutral ground at a park, but it didn’t seem to make any difference.

Has anyone dealt with this? What can I do to help them eventually coexist in the same room without my 1-year-old being so reactive? I don’t expect them to be best friends immediately, but I’m worried this won’t get better.

Any advice, tips, or personal experiences would be super appreciated!