Singular or plural

[tryingtokeepintune]

Help! Getting confused as to whether this sentence should be:

Kate, as well as her friends, is not well/happy today

Or

Kate, as well as her friends, are not well/happy today.

I have seen both used but which is correct?

TIA

The first one is correct. You could remove the "as well as her friends" and it should still make sense. The person who isn't well/happy is Kate and she is singular.

Kate is not well or happy today, and neither are her friends.

They're both hideous. The first is syntactically sound.

I have just vomited through my nose. MNHQ should put a trigger warning in the title

Prism has got it right.