Have a male betta in 5 gallon tank wanted to add some tank mates so added 1 female Platy the betta just chases it around and flares What to do?

I put sharky in timeout. I moved him back to his small aquarium, he is pist. Did not think the Platy would make it through the night. I am thinking of getting different color platies. Then re-introducing sharky later and see how it goes. Appreciate any help if anyone knows how to calm down an aggressive betta? Had him for a year.