Help me understand what was my fault..

"I'm a 28 Muslim girl, who got married in my second year of college to my first husband. We didn't know each other well, but I agreed due to pressure from my parents. It didn't work out because he didn't want me to continue my education and would abuse me with harsh words and insults. I refused to drop out of college, and we eventually separated. I had a daughter, continued with my life, graduated, and started volunteering in companies, doing social work.

After three years, I married another man who already had a wife who is infertile and she was the one allow him to marry second wife so he can have kids ( i didnt knew this, i mean abt his wife infertility) According to Islamic law, it's permissible for him to take another wife. I didn't know him well; he was introduced to me by someone at my parents' home, and I agreed. He was a good person, and I enjoyed a happy life that I hadn't experienced in my first marriage i did everything i can to make my husband happy. We had twin boys, but after giving birth, I started noticing changes. His care and affection decreased, and happiness felt forced. Life went on, and after two years, I discovered he had a side chick for almost seven years, even before marrying me. They would break up and get back together repeatedly. He started telling me that the first wife knew and didn't say anything so why would i make it like big issue, and life goes on.

I was hurt, and I realized I had started to love him deeply long ago. My heart was in pain i cant explain even though i was hurt still i love to see him smiling be success and etc i cant controll it, and but everytime i try to talk to him about his behaviour ge gets it back to me, I felt immense pain, even considering suicide. Since then, we've had no understanding, and it's been five years since we got married, but we still don't have the same peace as before. Now, we're just arguing. My heart is tired, but I'm thinking about my children. I'm worried about what society will say if I get divorced again.?will i ever experience the real relationship happiness..? What will happen to my children? Currently, I'm working in the Gulf countries on a two-year contract, trying to save some capital. When I return, I want to ask him for a divorce and start my life with my children.

Where did I go wrong? Why do I try so hard with husbands but still end up hurt and even divorces? What should I do? The worst part is that I still love him deeply, despite the pain.What to do to remove this pain?"