Ugh what to do??

Long story short: I had a guy friend for several years that I was very close to. He was everything to me. I was either in love with him or very close to it, and he felt the same way. We quit talking when I got serious with my now husband and it was really hard for me to accept that our friendship was over. It took me probably a year to accept. 
3 days after I got married he messaged me and said he missed me, would always be there for me, I was the one that got away, etc. It made me angry and I haven't spoke to him since. 
He re added me on FB yesterday and sent me a message. We chatted throughout the day and just caught up on the last few years. I haven't said anything I wouldn't want my husband to see and he wouldn't care that I'm talking to him again. But I feel guilty!! I have butterflies that I haven't had in years and couldn't stop smiling all day. I don't think I can handle losing him again but I know I'm walking a fine line.