I would say "(Надо же,) какая у тебя насыщенная жизнь! / Офигеть, какая жизнь-то у тебя насыщенная!" 😁 Остросюжетная is also totally fine, though it wouldn't be my first choice only because it's hard to pronounce and I'm a lazy ass 😂

hahaha, thank you!

So, "My but" is a lead-in?

Yes it is. You can also just use "my" and it precedes an evaluative comment: My what a beautiful house! My, but she's a pretty little girl. My, but you're a hard worker. "my but" is a little "old-world" - people don't really talk like that anymore, so it makes a statement like this post more sarcastic.

Great, thanks! good to know 😀

Also, women tend to use "my" more than men.

I see, it's more typical of women ). My, but you're a hard worker. Как я погляжу (видно), ты трудяга. My, but she's a pretty little girl. Да я смотрю, какая она девочка хорошенькая.