Hazardous cleanup

My brother has dealt with mental illness to the point of disability for nearly his entire adult life. He lives with my husband and I in our basement. One of his big triggers is being spoken to at all about cleaning and I try really hard to respect his space and privacy. However, I knew things were bad just based on the smell upon entering our house. He’s always home and confrontation of any kind, no matter how patient or compassionate, is met with total shut down from him. I’ve told him I will help multiple times before but he continues to tell me it’s under control and the best it’s been in a long time down there. He recently went to visit our cousin for several days and I went down there. I’ve gotten a good amount of trash out, but it’s so much worse than I imagined. I don’t want him coming back to that, it cannot possibly be okay for his mental or physical health. Not only that, his poor cat that is subject to this as well. I’m doing what I can to fix this but there’s a lot of biohazard and I don’t know how qualified I am to do this. We’re talking mold, mildew, excrement, and water damage. I have cleaned this up before when he has gone inpatient, but this is much worse. Has anyone had to get hazmat cleaning done and how much was it? Was it worth it? I’ve sent off for quotes but with it being the weekend I don’t know if I will hear anything. I don’t know if this is something I can even afford. I was hoping to get this done before he gets back on Monday but I’m so overwhelmed.