How to repair a friendship?

Hello, I was wondering if anyone could help me. I’m not sure how to repair a friendship. This all happened online but it involves a friend I know in real life who I have met many times, have even been on holiday with and who is also part of several friendship groups, so we have mutual friends. We've been friends for 4 years and she is a number of years older than me and I was very surprised how this all escalated.

I guess it began with me doing something wrong - oh no! Before Christmas, prompted by someone in our friendship group who sent Christmas cards and then apologised to everyone for sending them, I responded within our small group that people could do what they liked - send cards or not, but I felt sending Christmas cards was about getting in touch with people you care about and especially in the case (obviously this did not apply to anyone in the group) of people you didn't see or speak to often, but did think about and hope were ok. I also said I didn’t like it when I sent someone a card and they didn’t even say thank you, but instead merely replied “I don’t send cards, I’m giving to charity.” All I need is a thank you I said, not a card or any explanation for why they’re not sending cards. This was all in reference to no-one in particular and I said it only in our small group, not publicly. I suppose I was frustrated at the time myself as I had spent a long time and a lot of care writing cards to many people and I had spent a lot of money sending them too even though I was overdrawn and struggling financially and I was annoyed by the number of people boasting online about their charitable giving truth be told (you don't need to crow about donating money - just do it!) Anyway, one of my friends (who doesn’t send cards, but hadn’t annoyed me) became upset, removed herself from all friendship groups and posted a very cruel tweet publicly, directly about me.

I got in touch with her to apologise as she'd clearly been upset by what I had said and to confirm that I hadn’t meant her or anyone specifically. I also left the groups too so she could rejoin if she wished without me having to be there. I couldn’t hide I suppose that I was now hurt too - that someone I cared about could not only send a mean tweet directly about me, but since when she suddenly left all these groups everyone else in the group was saying “Is she OK, is she OK?” (I didn’t leave the groups without sending a message to say why first.) and the reason she wasn't OK was obviously just: me. This was just a few days before Christmas.

She apologised to me a few days later and I felt slightly wary but it was all fine, but in the next few days and weeks, any time anyone tweeted me, or if I didn't like a tweet she'd been tagged in too by someone else, she’d make an irritated comment on her twitter and because she’d tweeted about me before it was hard not to presume she was referring to me again.

I tried to ignore it, but in the end it had happened enough that I thought if something is unresolved I wanted to resolve it and one of us had to be the person to properly attempt to resolve it, I felt, so I messaged her (only once) to ask if everything was ok between us and sending good wishes and she replied in capitals telling me not to ever message her again.

For a month she did not message me and I was removed from other groups (which I wondered if she’d asked the group leader to do. But it could have just been chance/other reasons.)

Today, a month on from telling me to never contact her again she apologised and said she understood if I didn’t want to reply or have anything to do with her ever again, but I said it was fine and sent her well wishes, saying I was glad she felt better. It was pretty formal, but she apologised and I accepted.

However, I feel I can’t trust her. I don’t know what to do about it. I have not spoken to anyone about this, but I wonder if she has spoken to any of our mutual friends about me?

I don’t feel I want to write anything at all on social media anymore and maybe it’s fine to just not do that (although it makes my life pretty lonely as all my friends live far from me), but since we have mutual friends it is likely we’ll meet in person again someday and I don’t know what to do about it. Also no-one will know about the situation except me and her (unless she's told anyone) so won't understand if there is awkwardness.

Unfortunately all this came during a particularly bad Christmas for me too when I spent weeks and Christmas Day entirely alone so I was not only alone but had no escape of being online during this time. (I’ve pretty much stopped using twitter because of it.). She also told me never to contact her again on News Year's Day, so it wasn't the best start to 2019.

I don’t really want to discuss anything further with my friend. I think she’s made it clear I’m not a close friend (during the month she’d told me not to contact her, she was still interacting with other friends online - those who are not mutual friends.) I do wish her the very best, but I will be wary of what she ever knows about me now. Which is difficult as we still follow each other so it means I have to be wary of anything I might say. I didn't want to unfollow her as I feel it is petty and I do care about her.

But the whole event has left me feeling very miserable. I can’t make myself leave the house for things I would a few months ago have done without a second thought. I don’t know how to get beyond it. I have never lost a friend before and now she has apologised which I accept and thank her for, but unfortunately I can’t bring myself to understand how someone could say something and not think or care about the impact that might have on the person you said it to for a whole month. I suppose in that month the only thing I could do, since I wasn’t allowed to contact her was to distance myself from caring about her and to try to distance myself from considering we're friends.

But I don’t know whether it is best to remain cordial but distant (and if so, how that can work when we have mutual friends who know nothing about what went on) or to try to get to a point where I can forget it ever happened. And if the latter - how can I do that?

I guess I would like to repair the friendship, but I feel like I can't talk to her and I don't trust her which doesn't feel like an ideal basis to begin upon. I also feel like maybe she didn't ever consider me a friend to the degree she might other people.