Me[17] and my boyfriend[18] have been going through a rough path and I really messed up and he's willing to give me another chance, any advice?

Hello I'm writing this as a last resort as I do not know how to do better as I've truly messed up, this is my first ever relationship I also barely talk to people and also my first talking stage but we are in and long distance relationship and before what I did we haven't been okay for a couple of days we both wanted to fix it but couldn't so we've been awkward with each other and couldn't talk much since he have been sick for a few months now

We haven't been talking much until yesterday where we had an argument because of me, for context someone asked to be my friend and said he was gay I let him rant to me about his problems(this is all online btw) I did ask my bf beforehand if it was okay for me to talk to him he said it was okay but I should've known it wasn't

afterwards the dude told me he was joking about being gay Idk if it matters but I wasn't really engaged in our convo but I didn't reply afterwards and went straight to my bf apologizing for talking to him since he considers that kind of thing as microcheating but he told me theres no point since he still considered it microcheating even if he were truly gay.

I've truly messed up I know, but I'm failing to comprehend why would he lose trust at me when I didn't have intentions to find someone else, I'm sorry if my question sounds ironic I don't communicate with alot of people but I should've known replying wasn't okay since I knew he was the jealous type and even blocked my friends for him so I can't exactly ask anyone else for advice

He said he is willing to give me another chance to prove its worth staying any advice is greatly appreciated and please help me understand why it was so wrong of me to do that I've been apologizing nonstop but it feels like empty words considering I still don't understand the extent of what I said. You are free to be mean and not sugarcoat your words aslong as it's able to make me understand so I can be better, how exactly can I convince him to stay?