helpppp I need a backbone

Soo i got a promotion in march and was made a manager at my law firm. We just hired a new employee last week and it's just not working out. This was not an entry level position and he knew that and stated he had experience. Now I get that he's still new and learning but you can't teach the things he's asking. I'm working in a fast paced environment and if I have train someone how to properly write a letter and th difference between "was" and "is" it's just not going to work. He wrote me an email today and address it to Alyssa and my name is Alison. He's almost fallen asleep during training and not really taking any notes, just not what I'm looking for. Well I did speak to my boss and she informed hr and. It we have to give him a verbal warning tomorrow that basically says he's not paying attention, needs to stop excessively using the restroom (unless he has medical reason), and that he called me Alyssa in an email . I'm going to be completely uncomfortable bc I'm not good with confronting ppl. I'm good at my job and what I do but I get very nervous when I have get someone in trouble, I feel bad. Any advice would help.