accused of plagiarism/collusion what should I do?

All options stink, you were daft. Your 'friend' is nothing of the sort.

I suspect your best bet is honesty that you broke the rules and shared your work, and were then a victim of plagiarism. Saying you both planned it is collusion and debatably even worse. Your 'friend' has totally made a sucker of you and actually has the cheek to ask you to take equal blame...

I mistakenly sent my work to my friends show were rlly struggling with their assignment thinking they would use it as a guide, but turns out they copied the whole thing and now I’ve been accused of plagiarism and have a chance to provide a written statement. My friend have said that we should say that we planned it together, but I don’t know if this is enough so that I don’t get a complete 0. I don’t know whether to just own up and say I sent it to them and they copied it or to go along with the idea that they planned the work together?
what should I do?

Speak to your SU for advice and come clean. Getting 0 is the least of your concerns depending on your university's policies surrounding these matters.

Did you not pay attention to the academic misconduct lectures/talks/emails given to you at the very start of university? How could you have done this...

I know it was so stupid. We had a tutorial about plagiarism, but it was mostly about copying others work, nothing about sending work, but it is still my fault for being dumb enough to even do that. I just wanted to be helpful and they kept asking so in the end I just sent it to get them off my back

I mistakenly sent my work to my friends show were rlly struggling with their assignment thinking they would use it as a guide, but turns out they copied the whole thing and now I’ve been accused of plagiarism and have a chance to provide a written statement. My friend have said that we should say that we planned it together, but I don’t know if this is enough so that I don’t get a complete 0. I don’t know whether to just own up and say I sent it to them and they copied it or to go along with the idea that they planned the work together?
what should I do?

I know it was so stupid. We had a tutorial about plagiarism, but it was mostly about copying others work, nothing about sending work, but it is still my fault for being dumb enough to even do that. I just wanted to be helpful and they kept asking so in the end I just sent it to get them off my back

It's not your fault - don't worry! But remember this as a lesson for the future. It is good to be helpful and be kind, but like others said - some people (like your 'friend'), will take advantage of this. If someone is struggling definitely try your best to support them but don't send them your whole essay!

I'm not in favour of kicking them when they're down, but it IS their fault, rules = broken or they wouldn't now be in this situation. Also they should totally worry imo, they are presently at risk of expulsion, how they present themselves next will be key.

I know it was so stupid. We had a tutorial about plagiarism, but it was mostly about copying others work, nothing about sending work, but it is still my fault for being dumb enough to even do that. I just wanted to be helpful and they kept asking so in the end I just sent it to get them off my back

I mistakenly sent my work to my friends show were rlly struggling with their assignment thinking they would use it as a guide, but turns out they copied the whole thing and now I’ve been accused of plagiarism and have a chance to provide a written statement. My friend have said that we should say that we planned it together, but I don’t know if this is enough so that I don’t get a complete 0. I don’t know whether to just own up and say I sent it to them and they copied it or to go along with the idea that they planned the work together?
what should I do?