I will start out by saying that you are totally normal (and so is he) for feeling the way you do. I do not think men really will EVER grasp the enormous task that being a mother is. They just aren't made to. However, hopefully y'all can learn to work as a team, instead of working against each other.
This will probably sound unorthodox, but if you begin to meet his needs more, he will do the same for you. One of you has to start and consistently CHOOSE to love, no matter if your own needs are being met. It is sometimes a difficult choice to act out, when you feel so angry. But, it works. I know, I have done it.
My husband and I have read a great book called the Five Love Languages by Gary Chapman. In it, he discusses (through 12 years of marital counseling notes), what he found to be the 5 main needs that people complained about that were not being met. They are: Words of Affirmation (praise and thank-you's), Quality Time (spending uninterupted time with them), Gifts (little goodies), Acts of Service (taking out the trash, vacuuming, etc.), and Physical Touch (holding hands, not just having sex). Dr. Chapman explains that when our main love language is not being spoken to us, our "love tank" gets emptied and how we need to learn to speak the OTHER person's language, not speak our own to them. Often, couples have different languages and this causes a breakdown of communication, anger and unforgiveness.
This book has been a great help to us even now that we have been married 6 years. Our first child arrived last August. I work out of our home, tend the baby and my husband does construction and side jobs as well. We have an extremely full and busy life. I was basically starting to feel like I wanted to leave. I wasn't getting any help with the chores since he was busy working for everyone else, but I was left out. Since I was angry, I certainly wasn't going to tell him he was doing a good job!! My love language is Acts of Service and his is Words of Affirmation. Once we revisited our languages, we have both been making an effort to speak the others' language and things have been a great deal better.
One other thing, since I have gone on and on!! Try to put yourself in your husband's shoes. He is probably nervous and fearful about the new business going well and how he will provide for you and the girls. He also may be feeling a bit of a failure because he knows he hasn't been helping, or spending time with you and the kids. Men are often more sensitive and fragile than we think, or they EVER let on. Most of the time they don't know what they are feeling, let alone how to express it! I know it is like pulling teeth to get my husband to talk most of the time.
I am sure you know the REAL issues have little to do with whether or not you are having enough sex. That is just the way it is coming out. Y'all need to talk, forgive and CHOOSE to love each other. Maybe you can get a housekeeper to help you with all the chores? :)
Hang in there!