My boyfriend still having pictures of his ex on his phone and still wears his t-shirt

Hi, this post won’t be here long, at least not until I get some replies. My (24 m) boyfriend (24 m) have been together for 5 months or so. He’s very sweet and loving and I have never been so happy. Everything is great for the most part, but there is something that is seriously bothering me. He still has pictures of his ex boyfriend on his phone. To clarify these aren’t pictures where the background is the main focus of the image, these are pictures where his ex is in the middle and is the center of focus. He has multiple of them, not just one too. I also found out that he has been wearing his ex’s shirt as well.

I want to clarify as well, this is an ex that he has admitted he was particularly heartbroken over. They didn’t so much break up as they were forced apart. He has saved cards and letters from him and keeps them in a box of “important things.” Am I overreacting and just being ridiculous? I really want us to work, but I am finding that I am crying more than usual and it’s always over this. Whenever he mentions him my mood plateaus and I get irritated. When he finds out I like something that his ex likes, he says “(his name) likes that too” or “(his name) liked that/them.” I am also so confused by this because his ex really didn’t treat him well at all.

I am probably just being over emotional or overthinking it, but I wanted at least one second opinion before I bring this up to him.

Tldr: I am upset that my boyfriend still has pictures of his ex on his phone and still wears his t-shirt, am I overreacting about this?