Is it petty??

So I’m happily in love and engaged to the man of my dreams and we are getting married next October. An old flame from 4 years ago reached out to me on social media asking “how are you” things ended ok between us but I feel if I don’t respond it looks petty, but at the same time if I do respond and tell them how happy I am and I’m doing great I still feel petty. Not sure if I should reply back or just ignore it all together.