breakup 2 months ago, ex was still texting me every day, told me yesterday he's seeing someone new

I (28, F) was with my ex for 2.5 years. He broke up with me just before my birthday.

He'd been struggling with his mental health and unable to commit to the relationship, as he struggled to know if it was "right" and couldn't imagine the future. He was sobbing as he broke up with me and holding me. After, he kept messaging me every day, keeping our routines, still sending me good morning and good night messages, saying he loves me every single night. He's told me the breakup was hurting him, that he's really sad about it, that he thinks about me a lot and misses me all the time 2 weeks ago. His messages were always really affectionate, with kissy emojis etc. I think this really made me hold on to hope that we'd get back together. That he'd change his mind. I thought we were going through this painful breakup together, and even though everyone said I should go no-contact and what he was doing was confusing and messed up by continuing to talk to me as if we were still together, I always defended him and truly believed we had something really special and he just needed time. He had also started his antidepressants which I thought was a sign he was finally ready to address his mental health and, considering how he was still talking to me several times a day every day, that once he was in a better place he'd reconsider.

Last week he started messaging me goodnight later and later, and started taking longer to reply. But he was keeping the same romantic/affectionate style, so I ignored that tugging feeling telling me something wasn't right. Then on monday he disappeared, and I was really worried because he messaged me every morning without fail. I finally heard from him at night and he apologised, but by then I didn't really want to talk as I was upset. He messaged me goodnight as he normally would. But no goodmorning message. The next day same pattern, he said he was sorry, said goodnight, that he loved me as he did every night, etc. Then yesterday he messaged saying sorry again, and I finally replied. He then told me he needed to update me on something that wasn't going to be nice. And in my gut I knew what was about to happen, but I just thought it couldn't be true. But it was, he told me he started seeing someone, said he wasn't looking, it just happened. It's only been 2 months since we broke up. And he was still messaging me every day. He said he was sorry, that he cared about me a lot. But that things had "progressed" this weekend and he no longer felt able to talk to me as we normally did.

I felt sick. I threw up after our brief phone call. I still can't believe it. He still messaged me good night during the weekend, still told me he loved me, while he was with her. Who does that? How could he? I'm so sad, Im so mad. I feel sick every time I think about it. How could he tell me how sad he was 2 weeks ago? tell me how much he missed me the friday before he got with her? I feel betrayed. I feel like I meant nothing. No one who's so sad about a breakup manages to move on that quickly.

I guess I just needed to vent. If you have any advise I'd love to hear it. I'm also looking to connect with people who are going through a breakup, if you want someone to talk to I'm here! Send me a message and we can vent and support each other