What is the right thing to do?

I’ve been friends with this guy for about 9 years, but not close. We mostly just celebrate birthdays together, and an occasional hang out every 3 months or so. We text all the time casually, mostly just about life events or our days. Very general. Every relationship I’ve been in they’ve met him, they get along. It’s never been an issue. Until he sent me flowers earlier today, the day before valentines with a card saying “happy Valentine’s Day”. He never flirts, never compliments me, always been a friend. The same way I have girl friends. But this was very sudden and I don’t know if to read into it or to talk to him. He doesn’t know I got back together with my ex because I’m secretly ashamed I took him back and don’t want to face any judgment. I told him thank you for the flowers and I let my boyfriend know. My boyfriend said he probably likes me and to cut him off. I want to respect his feelings. I just don’t know how to handle any of this. What do I say to the friend? I don’t want to hurt anyone.