Firstly we have a cultural issue. I see you are from India, I am from Australia. Where I live, it is illegal to beat children. It is illegal to hit them with any object, near the face or head and many people do not like giving toddlers a smack with an open palm on the bottom. So this presents some difficulties in addressing this issue. Being mindful of the cultural differences, I am going to answer this question, from a global viewpoint of what all children thrive on and need from their parents.
The problem.
Your partner is away much of the time, so this puts a lot of pressure on you as a parent and it is important to have support and breaks as a parent. Having a renewed sense of purpose assists any parent. When you feel your irritation begin and your anger rising, you must remove yourself from the situation. Give yourself a time out, not as a punishment, but as a breather. To give you time to calm down and gain perspective. As the current cycle of behavior is not working for you and your son.
Allowing your son to hit you to appease him is only encouraging very bad habits. It is encouraging him to disrespect you, use his fists as a way of solving his bad feelings and removes any authority you have over him as his mother.
Beating your son teaches him that violence is an acceptable response to frustration. It demeans his self worth and the respect between you both. There is no example for him to learn to deal with irritation, except to become physically violent.
It is perfectly normal for children to require constant reminders and pressure to do homework and many other daily tasks. As you know this is an area of conflict, it may be better to let homework slide for a few weeks, until you can gather some more emotional energy and control.
At the end of the day, he is not completely in this environment effectively, he is growing bigger and stronger each day and the problem is going to become one you cannot rein in, if you don't take action. There is no point pressing a child to do homework, when there is violence in the home. Clean up the violent outbursts and then you can take stock of homework and other tasks.
Currently your son sounds angry and resentful towards you, he knows by not dong his homework, it makes you crazy and for many children this gives them a great deal of satisfaction when they are unhappy with their parents or situation.
So you need to ask yourself what sort of man do I want to raise?
I have two sons and I approach it like this: What sort of men am I raising? How are they going to treat their partners? I want to raise men, that are respectful and protective of their partners, not men that will scare their partners because of bad tempers and physical violence. How do I go about this? By teaching them that how they treat me (their mother) and their sister, sets the stage for how they will be as adults. And it all begins with me, as their parent. I am responsible for directing this.
I am also a single parent, and truly understand the pressures and how we can get to a breaking point, or so it feels that way. The key is, this is a feeling and it passes, we will soon be feeling better, so it is vital to not do things in this state that will cause harm to our children or ourselves. We need to take care of ourselves to take care of our children. They see everything and we set examples for them continuously.
What can you do?
As I mentioned earlier, give yourself space when you feel irritated.
Change your routine.
Spend time having fun with your son.
Find out what he enjoys to do (as often parents can lose sight of this when in a rut) and do it. Go for a walk, anything, together and break that routine and take the pressure off both of you.
- Change your thinking about it.
By thinking your son is winning when he does not do his homework, it is helping the cycle to repeat. Change your thoughts and think, every time you do not beat him and every time you have an experience together where you both smile or laugh, you are both winning.
There is no easy fix. These words seem so flimsy to help your situation. It is just a beginning, to help you pick up the pieces and start again. In these times of crisis, sometimes we need to shock ourselves into a change.
An important issue that needs to be addressed is the type of support you have.
Seek good family or friends to help you. Spend time with people and see if there are activities that your son can do, out of the home, where he is safe and occupied physically (like sport). You both need space and some more happiness in this situation.
edit
I just read your profile, you have an older son. I would also be asking your older son for his help with his younger brother. This is something I have found to be invaluable. My 13 year old son spends a lot of time with his 19 year old brother. This has assisted a lot with his behavior problems and the conflict between us, as his older brother sets a good example (because he is older and through this difficult age) and my younger boy looks up to him in a way that they don't admire their mothers at this age.