You shouldn't, no reason to apologize for anything, everyone makes mistakes. Your English is a lot more understandable than many other Asian people I've snailmailed with too. All you lack is probably confidence... What kind of sickness do you have? Physical/Mental?
Anyhow, cheer up. The peoples of NG are always here to sympathize. :)
Crazy-Dorsy
Well, your English is understandable and your spelling is good, so it's not all bad. Please don't be sad! :(
Dei-Sama
Thank you but most often it is difficult to cope. :(