Trending @Infosys; Need some advice

I have been working with infosys for more than 5 years now. Recently,I was mapped to a new client where the project is in a critical situation with long working hours. Due to some personal problems, almost daily, I can't handle such long working hours and a hectic schedule. I don't have any dependency on the project. Even I asked for release from the project, but they are asking me to talk to HR stating as project refusal. Please suggest what should I do.