AITA for gossiping with a co-worker about another co-worker’s relationship?

I work as a nurse in a hospital. There’s been a rumour going around about one of my co-workers, Lucia, that she is in a relationship with our clinical lead, Max. I’ve been off on long term sick for a couple months, when I returned I noticed that there were a lot of whispers going on about Lucia.

During my break, I asked one of my co-workers who I am close with, Dani, if there was any gossip I had missed out on. Dani told about Lucia and Max, apparently Max had been giving Lucia lifts to and from work, and they had been seen out together a few times. Dani told me that she had seen Max and Lucia the previous night in a nice restaurant in town having a meal together and they looked very cosy. Dani also told me that since the rumours had started about Lucia and Max, Lucia had gotten promoted to the next band. I told Dani that Lucia didn’t seem like the type to sleep her way to the top. Lucia and Max being together had surprised me, they just didn’t seem like they were in a relationship. Together in the department, they are very professional to each other.

As I made the comment about Lucia, she walked into the staff room. She was rightfully upset that I had made the comment, I would have been but I didn’t think she would hear it. Lucia told me and Dani that we needed to stay out of her business. She also said that while she didn’t need to explain herself, no one knew she had applied for the higher band position only the nursing manager who had suggested she applied. Dani jokingly told her that if she didn’t want people to gossip about her then she shouldn’t be sneaking around with Max. I apologised to Lucia but told her that I agreed with Dani. Lucia just grabbed her lunch and stormed out.

Lucia has reported both Dani and I to the nursing manager, claiming we are making the workplace hostile by gossiping about her and claiming that she only got her job by being with Max. He has advised that we both need to apologise to Lucia and stop gossiping at work, he reiterated what Lucia had said, that he had encouraged her to apply and that was long before the rumours about her and Max started.

AITA for gossiping about a coworker?

Edit: I didn't realise it was an asshole move to gossip. Everyone gossips at work, it helps make the day go by. Even Lucia herself has. However, I do need to apologise to Lucia as this has clearly offended her. I will call her in the morning and apologise - we aren't on the same shift for a while as she's going onto nights and I would rather not wait until I see her face to face again.

Edit 2: I have spoken with Lucia this morning. I apologised for gossiping about her and that I honestly didn't mean to upset her, but I understand why she went to the nursing manager. I offered to take her out for breakfast after one of her night shifts to celebrate her new role and she accepted. So we have pencilled in a breakfast for the two of us at a cafe near work. Lucia said that she didn't care about people talking about her and Max, it was more the insinuation that she got her new position because of Max. She said that no one appeared happy about her new position when it was announced because people thought that she got it because of Max and hearing me say what I did really hurt her. While we were on the phone, I heard Max in the background, Lucia did quickly shush him when she realised and I told her not to worry about it. I could see she was happy, a lot happier than when I went on sick leave and that I wasn't going to say anything as it's her news to tell when she is ready and no one else needed to know. She thanked me and said they were keeping it out of work to be professional, its why they aren't telling people which I completely understand.