Eating disorder help

Long story short my fiancé has had issues with bulimia in the past. He had it maybe a few years ago and suffered with it for a year or more. This is what his sister told me. He never told me. We’ve been together for almost a year and there’s been at least 2 times I KNOW he threw up on purpose. I never mentioned it to him and I’ve never mentioned my concerns. I’m worried. I’ve never had bulimia so I can’t say for sure, but I’m pretty certain you don’t just do it once every now and then, right? It’s pretty much a constant thing? I’m with him everyday and I’m planning on keeping a closer eye on him. What should I do? He’s very secretive and he lies, big things little things, he lies. The good thing is he’s very very loyal and does so much for me and our daughter that’s coming in May. He cares a lot. I just don’t know what to do, because I don’t even know if he does it constantly. I don’t think he does, but how would I know? I’m not in the bathroom with him. I feel so sad for him, he struggles with his self imagine and esteem a lot. How do I help him recover if you think he does it more and how can I get him to believe that he’s beautiful the way he is?