Don't rub Beth's face in it; get "excited" for her!
"I bet you're excited Heidi is joining AGT. You two can swap model stories and fashion tips. #newBFF?"
Then go in for the kill.................
"I can't wait for the first pic of you two together on the AGT red carpet. #twotruebeauties"
Maybe even add a "Hey beautiful!" at the beginning. And make sure to congratulate her on her new show, but get the title wrong. Call it like "Pampered Pooches" or something.
This approach will do much more long-term damage than just Nelson-laughing at her.
I'd like to dedicate this post to Engaged Chicken. She "gets" me.