Feeling Excluded from My Family's Group Chat

I recently found out that my family has a group chat without me in it 😔 I'm the only one that's not been added. What's worse, even my sisters boyfriend is in it. I often feel excluded by them but this was another level of low. It's just made me feel awful and I'm having to reconsider the expectations I have for them. I confronted my mum about it and she apologised for being "thoughtless". I just think it says a lot about how much they all care about me and how they view me. This has just consolidated the way I feel :( it's hard to understand them and it leaves me wondering what it is that makes me so different from them all? I don't think I've ever done anything to them, they're the ones who have always hurt me. Idk man I'm fed up with it