How do I get past this breakup?

Very quick backstory – a few months ago, after 8 years together (we were engaged) he said that he wasn’t feeling “the spark” anymore. It had been a tough few years – sex had dwindled to barely anything, I’d put on weight (he had too), we’d both gone through mental health issues even before COVID, he had a tough death in the family, we bought a house, he was made redundant, I had a toxic job and we both found new jobs. He was smoking weed daily. I was off and on struggling with anxiety and depression, which I sought help for but it kept sneaking back in. But also, we had a lot of amazing times – a shared hobby we’re passionate about, a large shared group of friends, a fantastic “partnership”. We were best friends and a great team.

After he said he wasn’t feeling the spark, we sought out therapy and uncovered some issues – I was closed off at times, and he was difficult to talk to. Very chicken and egg stuff. We both tried – I lost weight and tried to be more open. He tried to be more patient. I saw what he saw – that I was scared to enjoy things, said no when I sometimes should have said yes, and was living a smaller life than I wanted to. But it was too late, and he’s broken it off.

We are still living together, and when we’re both in everything feels pretty normal. We talk more than we did in the last bit of our relationship. We eat together, watch TV, and even cry together. He said yesterday he wants us to still be best friends, though it’ll take a lot of pain and adjustment in the meantime.

I still hold onto the tiniest hope that we could work out. Initially, we were going to go on a break, but he’s said he doesn’t want me holding onto hope. So I guess it’s unlikely.

I’m seeing a therapist but she’s not great so I’m trying to find a better one. And in the meantime, the last few days I’ve shed my body weight in tears. I can’t stop. I’ve read, I’ve written, I’ve walked, I’ve talked to friends. Everything reminds me of him, and I miss him and the future we’d talked about.

And I kick myself over a million regrets. I wish I’d sought different help sooner. I wish I’d worn my hair down more. I wish I’d been less defensive, and open about the ugly bits of me, not just the bits I wanted him to like. Fuck, I wish I’d worn my engagement ring more. I didn’t wear it daily because it felt too precious to wear every day, and I was scared to lose it or damage it. And maybe some of me didn’t feel worthy of it? I don’t know. But I wish I’d worn the fuck out of it because now I can’t and I miss it.

I don’t know what to do next. Everything feels hollow. I don’t WANT to batch cook for one. I don’t WANT to see my friends because I miss OUR friends and that life. Our shared hobby feels haunted by memories of him. The house that we just finished fixing up is built to our specifications. Nothing feels good. I don’t know how to begin thinking about a new life when I want my old one back, and can’t imagine something better than what I had. All I can see is what (and who) I lost.

TLDR – Boke up, still close friends, I don’t want to lose him from my life and don’t know how to begin getting over him.