Broken and Confused

A few days ago I was using my BF’S phone and I went through a message with his friend. I read the message and I felt so devastated. Because in the message he was venting to his friend that he isn’t in love with me anymore. We live together have over 10 years together and my heart and soul completely shattered. I lost it. I wanted to confront him about that message but I didn’t want to tell him I was going thru his phone. I’m just so confused because his actions towards me are different. He tells me he loves me and is very affectionate and loving. So I don’t understand why that message to his friend venting that out. After that message I can’t be the same. I’ve been a little distant. My heart is still shattered because idk what to think or believe. What do you guys think?