My marriage is crumbling

As Salaamu Alaikum, I really need some guidance. I'm hoping to hear from Muslim sisters, but brothers, if you can share a man's perspective, that's welcome too. So my husband and I married young-I was 20 and he was 21. We've been together for 8 months now, but about 4 months ago, I discovered he was pleasuring himself to images of women on social media. I already struggle deeply with how I see myself and have body image issues, so this shattered me. We’ve been trying to heal, doing couples counseling, taking breaks, but it's been so hard. Until six weeks ago, it was a painful loop: he'd do it, I'd find out, confront him, and he'd lie. It completely broke my trust. The last time I caught him was late May. I pleaded with him to be honest about whether he'd done it on YouTube (the only app left on his phone), and after swearing he hadn't, he finally confessed. We took two weeks apart, and slowly we're trying to rebuild, but the hurt is still fresh. Even now, when we're at a restaurant and I see a woman who looks like those he watched, I shut down emotionally and start overthinking nonstop. But the worst part... early on, I found my cousin’s name in his search history. He insisted he never acted on it, just searched her out of curiosity. I believed him because the alternative was too horrifying-she's like my sister, and we've all spent time together. But last night, the topic came up again. I begged him for the truth, saying Allah would expose it one day. After more lies, he finally admitted he had done it to her. He says he's done lying now, but after all the deceit, how can I trust that? I feel sick, I can't eat. I love him, but I feel like a fool for believing him. I know masturbation can be an addiction, but involving a family member feels like a line that just shouldn't be crossed. I've told him so often that I feel ugly next to her, and now this... I feel utterly hopeless. Is there any way to fix this? (I know we married young, please don't focus on that. Before marriage, he seemed perfect, our families are very close, and we did everything Islamically. It all felt so right.)