Fearful Avoidant Attachment style vulnerability (HELP URGENT)

I'm some who's a fearful Avoidant. I find that I have a lot of anxious thoughts regarding insecurities (overthink a ton) and I also sometimes have the urge to run away. I have this friend who I've been friends with for maybe 3 days now? Hasn't been long, but I really care for them, and so I've been having anxious/aviodant thoughts about them a lot. I'm also terrified of being vulnerable. I feel bad after being vulnerable, due to the fact that my family used to shame me, and even called me "annoying" after I asked for reassurance. Since then, I feel guilty and like I'm a burden after being vulnerable or asking for reassurance. Today, I was chatting with this friend, and I suddenly decided I wanted to come clean with the fact that I was a FA. I sent them a text, saying something along the lines of "I have to get something off my chest. It's about insecurities of mine. We don't have to talk about it.". They didn't respond at first, which was extremely hurtful. I tried to be vulnerable, and it seemed like they had ignored me almost? I freaked out and sent a message saying, "actually I'm not comfortable sharing this.", but I was still very hurt. Felt intense feelings of wanting to run away. They messaged me a few minutes later, saying they were in the car, and that they were back. Though they didn't acknowledge the emotional message from earlier, though they might've ignored it for my comfort? I tried to be "normal" and act normal, but I couldn't help it, I was even more hurt now. I asked them if they were ok to talk after they got back from the store, to which they said it was fine. So now, I have idk time before I have to be vulnerable and share this stuff. Idk what to share and what to share? Should I tell fully that I have FA, should I tell them I have insecurities and that I sometimes feel the need to run away? Should I tell them I felt hurt when they didn't respond to my message, even tho they probably didn't mean to hurt me? I'm afraid I'm going to self sabotage by opening up about this to them. What if they're uncomfortable with this, and our relationship changes? I'm too afraid to stop this now? Wtf do I do?? Help please...