Idk how to feel

Earlier my SO and I were driving to go someplace, and we were talking. He said my brother sent him pictures and he opened the message and said “why would your brother send this shit to me” I replied with what and he then showed me. It was two pictures of naked girls. I then called my mom and talk to her ( my oldest brother lives with our parents) she told me to talk to my brother so I called him and asked him why he sent my SO those pictures. He stared laughing and said it was a joke. I started telling him it wasn’t funny and disrespectful to me. Well later on he texted me apologizing non stop and blah blah. I appreciate my SO telling me and showing me instead of hiding it from me but I can’t help to stop thinking if he really wants to be with me anymore or if I’m good enough anymore. I’m really insecure now after seeing those pictures that my brother thought was a joke to send. Please don’t be rude.