Cat is now aggressive after new kitten was adopted

Hi so we have a 1.5 year old (Anakin) and he is the best boy ever. So chill and nice. He loves everyone and has literally never hissed. Biscuit (unsure of age—roughly 3-5 years) showed up at our back door in the middle of winter last year so we took him in.

I tried to find if he had an owner since he was so friendly, but no microchip and the humane shelter said they would just neuter and release because they were over-full, so we got him neutered/vaccinated and let him stay.

Anakin and biscuit became friends and we didn’t have many issues with biscuit. He’s peed on the bed a few times in stressful situations (vacations, house cleaners) and I suspect he’s sprayed in a few places but all-in-all it’s manageable.

Husband and I fell victim to a cat cafe a few days ago, and came home with a 3 month old kitten (We named her Calliope). She looks kind of like our long-time cat who we loved dearly. She passed away from cancer a little over year ago.

The issue is, Anakin loves Calliope, but biscuit has been acting very aggressive toward her and now he’s even batting at Anakin (they’ve always play-fought but this is just aggressive and not playful)

Calliope is lovely, and I don’t want to be that person who picks a new kitten over a cat we already had, so I’d prefer advice on how to correct the issues, but I’m not getting rid of her or Anakin.

When we first took Biscuit in, we tried to find him a home but didn’t succeed.