How do I handle this kind of woman?

Good evening people. Please don't mind my English. My post is actually out of pains and frustration and i may not type with the correct words. 

I'm a 31 years old guy. I'm actually very bad with spending because when i have money, whoever asks from me gets. I am under alot of pressure lately especially from those around me. I am the 1st child of my parents and have so many responsibilities. 

I got my girlfriend pregnant and she moved in with me. My parents were never there for me so i vowed i was going to be there for my kids. Hence i do all i can to make sure my daughter and her mum are OK. 

The girl in question is a torn in my flesh. Totally different from when we were dating without a child. Nowadays, as soon as i get my salary, she wants to buy this, she wants to buy that even though she knows i receive less than a 100k and i have multiple loans i am paying back because we moved out of our old apartment due to space constraints especially after she delivered. 

Whenever i don't have money, there is never a happy moment in my home. But if i come home and bring money, we become very good friends. She wants to live a good life which is not wrong but I feel when she knows how i am managing, she ought to understand and bear with me. 

The last straw that broke the camel's back was, i was yet to be paid, i had 700 with me. I gave her to make some food because we had the basic food stuff in the house.... Rice, beans, ogbono, spaghetti, garri, Egusi.... Palm oil. So basically all she had to buy was fish or something to put inside the food. 

I came home after a hard day at work and met an empty kitchen. When I asked for my food, she asked me what i expected her to cook with 700 naira. I got so mad and left the house but since it was late (it was close to midnight), i decided to come back. In my anger, i started asking her why she's treating me badly. And the next thing is, she called her mum to say I'm fighting with her and that i pushed her to the ground. Her mum replied and said that if anything happens to her daughter, she would hold me responsible. That she didn't give me a wife...... 

Now I feel i should just end everything and let's go our separate ways before it becomes a case of domestic violence. I never want to see my child grow up to see me fighting with her mum always and being unhappy. I believe a child that grows up in an unhappy home is always at a disadvantage. Please help me guys. I am in pains. What do you suggest I do?