I hate my stepson

I have been with my so for 3 years. Married for six months. I have a nearly 4 yr old from a previous relationship and my husband has a 7 year old son from his previous marriage. I despise the little brat. Honestly. It may sound awful but he bullies my son, he's pushed him down the stairs, constantly makes fun of him and I've just caught him telling my son to drink out of the toilet to name but a few things. I love my husband dearly. But I cannot deal with this kid. We're expecting in June and I honestly feel like I don't want this kid anywhere near our baby. I don't trust him. He's a spoiled brat. He's sly. I feel like a terrible person but I can't change the way I feel. I have tried. Is there anyone else out there who has been through this?