Ok, I assume(?) you are able to speak in a normal(?) modulated voice? If not, then you should start there. I know this is not impossible since I have a friend who is totally deaf--no hearing at all--. When I met her I (who am seriously hearing impaired) refused to believe she was deaf, because she speaks quite well with "hearing people's" volume and modulation. She also plays the cello by sympathetic vibration.

I am not a singer, but I listen a lot. Blues is usually sung from the deep chest using a lot of throat......if you understand that. With "Talking" type blues, tune is usually not too important. Match the vibration coming from your guitar to the vibration coming from your throat, and you will be close enough. There are lots of blues lyrics on line, including here in the Digital Tradition--the blue search box at the top of the page. You can also search the web for "blues lyrics".

I am sure that some of the singers here will be along to help you more than I can. Good Luck, and don't give up--I know you can do it too!