Made a mistake

Sitting here trying to figure out how I should word this but here it goes… I’m a 24F. In late April I reconnected with a guy (24M) from High School. At the time, I wasn’t interested in dating anyone so I just decided not to answer. Come early May I texted him back on messenger and exchanged numbers after a bit of texting. After the next few weeks, we were texting/calling each other everyday. Late May we decided to make plans to meetup for dinner. Which we did. It went great. Immediately following that evening; We started going on dates, hanging out all the time, spending the night at each other’s house etc etc. We did everything a couple does but In a very alarming short amount of time. I usually don’t move as quickly as I did with him (I regret it). Even discussed moving in together and started saving money to do so. Well, in July I had to move 45 minutes away due to a family emergency (needed to be closer) and that’s when the excuses started. I would ask him to come see me on the weekends and he would come up with an excuse everytime. Everytime we made plans I was the one initiating them (they never happened). He stood me up on my birthday even though we had made plans months in advanced. I saw him a total of three times prior to current events happening. I started feeling like something was off with him when the excuses started but I stupidly ignored the changes and told myself that he just was dealing with depression (that’s what he told me at first). Fast forward a bit, he started texting me dry and took longer to text back. Doesn’t call back. Still won’t make time to see me despite working only 5 minutes from my residence (yes. The whole time he worked close to my house and could’ve come see me before or after work ).September 20th 2023. I finally asked him what was going on and why there was a change. He explained it’s because he was trying to show me he wasn’t interested anymore but I didn’t get the hint. I asked him if there was another girl which he would not answer my question. Three days later, I had an instinct that he was with another woman. While at her house, he sent me pictures of her while laying in bed. Two days later He called me out of nowhere and had nothing nice to say to me. Degrading my body, my personality, qualities as a potential partner and a person in general. Told me I made up details about my miscarriage in late June, early July. (I’m not supposed to have kids… And I’m on birth control). After 30 minutes of that, he added the new girl to the call and continued to talk down to me and arguing with me. I said nothing to her because I don’t play games like he was trying to do. Well, after all of that finally stopped, she got ahold of my number and texted me.. Asking me what I was to him and what we were and for how long. When I explained everything to her, (she even agreed that he was a bad guy and everything?) She told me about the weekends he would blackout while drinking at her house and how lame he seemed to her… Exhausted by the whole situation, I just explained that I wanted my stuff back from his place and to move the hell on! She offered to drop it off at my house (I did not feel comfortable with that) so I told her no and if he won’t work with me then to just forget about it). Well, that’s where the conversation got weird. She asked me if she could call me and I stupidly said yes? Well, she proceeded to ask me about Him and how he treated me or why I was acting like I was towards the whole situation. Over the phone, she seemed like she was shocked by the behavior that I was describing. Even telling me that she is older than both of us and ‘doesnt play games ‘. That they were just in the talking stage. Am I stupid? Did I miss something? After explaining everything to her, she still chose to be with Him. In fact, they’re officially together as of a few days ago. I feel absolutely blindsided by the behavior of another woman and why she decided to get information out of me and still going after him despite knowing what she knows. In terms of him, well, I had a feeling this was going to happen or was already happening. I just didn’t want to believe it was possible. I’m feeling sorry for myself because why did I allow myself to go through what I just went through for someone that wasn’t officially mine?