So frustrated!

Its not even noon here here and I have already broken down in tears. 6yrs I have been with my wonderful husband, and I love him dearly, but he has this habit of not helping with house work. I'm almost 4mo pregnant and I take care of our three y.o. as well as work. After 6yrs today was my breaking point. I told him if he doesn't change I don't see us being together by the time the baby arrives. For the entire time we've been together he will make massive messes and expect me to clean up after him. I asked him to help me clean the house the other day and he finagled his way out by spending 45 minutes in the bathroom and then leaving to go get a drink from the gas station. It's the same thing every time I ask for help. I don't know what to do. It would break my heart if I have to follow through because he's an amazing father and loves us dearly, but I can't continue being the only one holding the house up when I work too. I just needed to get that out.