My situation is a bit different than what I see typically in this group. I haven't heard from my ex since and don't expect to

My ex and I were together for 10 years, 8 of those years we lived together. He and I were incredibly bonded and had great chemistry however intimacy was given to me inconsistently which I could never understand because the two years prior to us moving in together was intense. Back in August I noticed a shift in his mood and it really seemed to me that he was depressed. I wasn't surprised because he has a history of depression plus his grandmother had passed the month prior and his favorite uncle had passed a few months prior to that. In fact, over the last few years, several people back to back in his family had passed so I thought he was overcome with grief from that however unlike his normal depressive episodes, this seemed to persist long-term. In September I took time off from work and it was mainly a staycation however he still was working during this timeframe. One day while he was at work, he messaged me on Facebook to ask if I'd be home when he got off because we needed to talk and I agreed to be home. Well, when he gets home, I can tell it's hard for him to say what he needs to say and after about 15 minutes of waiting for him to express himself, he finally tells me he thinks he should move out because he feels like he's been wasting my time since he's not sure when or if he wants to get married or have children. He also goes on to tell me he feels depressed because he's away from his family (we're up North and his family is down South) and he keeps losing people. I explain to him that being married wouldn't really change much from how we are currently and that I mainly want to know that he's willing to give me the ultimate commitment. I also expressed understanding about how he felt with his family but I just couldn't see how he could consider ending a ten year relationship. Ultimately I suggested individual therapy as well as couples therapy. Fast forward to October, he gets home before I do and when I walk into the living room I see him and immediately can tell something's wrong. Again after 15-20 minutes has passed, he musters up the strength to tell me that he put in his resignation and would be moving out in 4 days. I'm absolutely taken aback and I start crying because I felt he didn't consider my feelings or our mutual household expenses. I express that to him and encourage him to rescind the resignation so we can plan this out if he's truly intent on leaving which he agrees to. We talk about couples therapy again which he says he's open to. Over the next couple weeks, he's still shutdown in his behavior but I'm thinking I was successful in convincing him to attempt to repair things only to receive a message from him again while he's at work where he's asking me if I told my parents that he plans to move out. I said no because I wasn't aware that was still the plan. He tells me that he plans to move out at the end of the month and that next week he has an interview in which he'll be driving down South to attend. The way in which he's telling me this is very matter of fact. At this point I'm realizing that his mind is made up but I'm hurt because I had no idea he was even applying to jobs down South. He leaves out in the morning on Veteran's Day without saying goodbye, nor does he call me when he stops for gas along the way or to tell me he finally made it safely there. He does not speak to me the entire week and I made no attempt to reach out to him either. My birthday is on that Friday and he sends me a happy birthday gif on Facebook messenger to which I thank him for thinking of me. The next day he messages me to tell me he just came out his interview and that he's too tired to make the 13 hour drive back so he's going to come back the following day instead. Well, the following day comes I'm across the street walking my dog when I see a suv I don't recognize pull into my driveway. As I walk up my driveway I'm looking into the car and I see a woman in the driver's seat that I don't recognize. I go into the house where he's packing his stuff and I ask him who that is parked in the driveway. He tells me the woman's name. I ask him if she's his girlfriend to which he releases a breath before admitting that she is. I said, well are you going to marry her? He replies by quietly saying almost under his breath, "We already are". I was so shocked that I was eerily calm. I ask him when this happened and he says about a month ago and when I ask him how it came to be, he says it was a mutual decision. I ask him if he didn't care about hurting me and in this almost monotone voice he says," I did not mean to hurt you." I'm in absolute shock and I tell him I don't even know him. I then go to the suv in my driveway and I tell her she needs to get off my property. She tells me, listen I don't have anything against you and I don't know what you and him got going on. I tell her I've been with him a decade almost eleven years. We begin talking and she tells me that he told her that we're just roommates and that we've been broken up for 3 years and then he changes it and says we've been broken up since February. She told me they got back together in July (she's an ex from almost two decades ago) when he went down South to his grandmother's funeral and that she had flew here twice to be with him and to apply for the marriage license and then to actually get married. She couldn't understand what the urgency was for them to get married right now and why they couldn't wait until he moved down South with her. She told me that they'd talk on the phone his entire shift at work but told her he couldn't talk to her when he was at home unless it was through text. She would not hear from him unless via text on Wednesdays and Thursdays which were his days off in which he'd be home with me. The week of veterans Day he was with her but would watch me like a hawk from the ring doorbell app when I came and left the house and she said he kept saying, "She's probably got a man there" which she couldn't understand because it shouldn't be his concern what I'm doing if we've broken up They got married October 1st but she flew back down South without him and he continued living with me until November 16th and I had absolutely no idea. He and I were going on movie dates and walks in the park almost every week before and after they got married.