My bf is still in love with his ex?

When I first started dating my bf he would always mention that him and his ex had a really toxic relationship and how he had to go to therapy to build himself back up after that relationship.

I asked him if he was over her and if he felt like he was ready for a relationship; he assured me that he was.

I later found out that they still communicate because they’re friends and he’s know her family for a long time. I explained that I was uncomfortable with that but I let I go when I saw that their conversations were pretty innocent.

I noticed that he talks about his ex sometimes, he’ll say things like "I’m so happy you did this with me, I did that with my ex but she it wasn’t a good experience " I was laying on him one day and the way I was laying reminded him of a funny story between him and his ex.

Yesterday he told me that the met because he had a letter for her. I don’t really remember how the conversation when after that I said « I feel like you like me but you’re in love with her » he’s response was maybe.

I’ve told me friends and they all keep telling me that they don’t believe that he’s in love with her but that he’s attached to her because all the toxic shit between them, kinda like Stockholm syndrome.

I’m confused.. I really like him and he treats me well, he’s honestly the best bf I’ve ever had but I don’t want to be stupid.

He sent me this message, trying to explain ig: