I (35M) am ruining our (37F) relationship with my self-hatred

Here's the scenario: we've been together for 8 years, moved in together, bought a house, have a dog, joint savings account. All of that. Likely not getting married (differential opinions about the state sanctioning marriage to the norm). My entire life I've been a self-hating asshole, and it's really starting to cause serious issues in my partner's and my ability to communicate. I see a therapist weekly, take medication, and in general try to manage my health. I just keep screwing up so damn much that I feel super unworthy of any affection.

At this point, I just have no idea why she wants to stay so invested in me and in spite of my attempts to improve my life, I feel like I'm only making her life worse. It's just so hard to bear down and not criticize myself every time I fuck up. It'd be one thing if it just affected me, but some things I do cause problems for our dog, or makes more work for her. In those cases, I can't help but feel like it'd just be better if I didn't exist. At 35, you'd think I'd stop being such a burden on the few people who choose to love me, but here we are.

From the tone of this message, you can likely tell it's exhausting to be around me. How do I stop being so exhausting and worthless?

TL;DR I'm bad at being a non-burden on my relationship. How do I stop being a burden?