Professionalism

Please correct my sentence?

One can have professionalism at doing one particular job at a time, he or she cannot be professional at doing multi job.

The situation is suppose I did something very worse to someone, now I want to apologise which is very hard because the person doesn't even want to see my see my face, so only sorry won't work here.

Can I say?

I am very ashamed in front of you for whatever I did to you.

Please correct me I just want to learn to say this type of sentences.