Husband talking to his ex on social media

What would you do if you found your husband talking to his ex on social media? They had a really tumultuous relationship but I know that he really loved her and didn’t want to end things. It’s been 8 year and now they have reconnected should I be worried and how do I confront him about the situation. I read their messages and they were saying they missed each other and both wished they’d married one another