[FULL] Ghosted Then Reappeared: My Ex-Fiancé's Return Drama

Ex-fiancé of 8 years broke up with me over text 3 years ago and disappeared. Now she is trying to rejoin our circle of mutual friends and I'm struggling with it extremely hard. Me and a girl I'll call Jessica were a couple for over 8 years and were engaged for 3 years. I met her through a mutual friend in my group of friends. We ended up hitting it off pretty quickly as our dorky and nerdy hobbies aligned really well. I personally fully expected to marry this person and spend the rest of my life with her. In early 2019, her job offered her an amazing opportunity to temporarily work for 4 months in the company's satellite office in New Zealand. She was an environmental engineer, temporarily managing and leading a new team. It was very sudden and I was not really happy with the idea, but she really wanted this chance and opportunity, so off she went. I flew out to visit her after about 2 months. Only when I arrived at the airport I got a text message from her. The message was short and more or less consisted of she was sorry but after thinking it through, she thinks it would be best if we went our separate ways from now on. She then completely blocked me on almost every single form of social media, cell phone etc. I was confused, devastated and became an absolute wreck. I remember completely breaking down in Auckland airport. I spent the next 4 days living at a motel, basically trying to get into contact with her in any shape or form. She had apparently blocked everyone in our circle of friends. Even her close friends from our circle of friends were shocked, confused and basically lost. Even her parents were extremely confused when I called them. Her dad, who I was extremely close with, we coached peewee hockey together and played a lot of beer league hockey together, refused to believe it at first. I was a mess for a solid year, but my close circle of friends managed to drag me out of my hellish hole along with some therapy. Her best friends became close friends to me. About a year ago, she invited some of her old close friends to her wedding, among a bunch of other people from our group. No one went and I quickly found out, which hurt me even more. Over a year ago, I started dating one of her old friends as me and her had gotten close over the last 2 years or so. She felt quite hurt when Jessica basically ghosted her. Unfortunately, there was some awkwardness because she fully knew I was not fully over my ex. But she has been a supportive and amazing person and I'm extremely happy with her. Life was going great for me. Then in December, Jessica apparently moved back home after divorcing a few months after getting married. I don't know much and I don't want to know. However, she is making this hugely concentrated effort to reconnect with people in our friend group, which is resulting in some very conflicted feelings for some people. Last week, I found out that Jessica and some of my friends have started playing D&D, which frankly made me feel like crap. Part of me just wants to move on from this, but I'm struggling hard. While my significant other has been extremely supportive, I just feel numb and don't really know what to do. Today, Jessica sent me a long Facebook message, basically apologizing to me for what she did and asked to be friends. I didn't respond and blocked her. I told my significant other and I just felt like I was going to break down. Right now, my significant other is saying she is worried about me and keeps asking me what I want to do. My significant other confessed that Jessica had sent her a similar message a few weeks ago and she told her off. I don't know what I'm supposed to do. I can't order my friends to not be friends with her. I just feel like a mess and I am struggling with this as I feel like I'm a teenager dealing with stupid drama again.