serious question about friendship ‘rules’

hi all, it sounds dumb, but i need some help with like… friendship faux pas. I’ve never really understood the secret ‘rules’ about friendship, which has ended a lot of connections for me in the past, and i want to avoid it this time.

here is the situation:

i am currently in a VERY down place. I don’t really want to go super into it on here, but i am struggling very much day to day. I have a friend who moved away last year that i still catch up with maybe every 3 months. Since i am having a super hard time and i don’t really have anyone else, I want to reach out to her to talk about what a hard time I am having, but i feel weird about it.

i feel like everyone always says to reach out to friends if you need help, but i’ve also been seeing a ton of people online that say that you shouldn’t be reaching out to friends just to get help/reassurance because then that shows that you don’t care about them.

this is confusing to me because it feels like two directly conflicting rules.

so now i feel stuck. I don’t want to make her feel that way. But i also don’t want to message her under the ‘guise’ of catching up with her if i just have this secret motive of talking about my problems. it feels like it’s a no-win situation, because reaching out at all now would be disingenuous.

the last time we talked, i complained about a family issue as well (and listened to her work problems), so i don’t know if now that established a pattern where it’ll seem like that’s all I talk to her for?

I’ve just had a lot of experiences with people spontaneously dropping the friendship if i do it wrong, and i don’t know what to do.