Thank you for writing. There are many levels to this question so I’ll try to respond one at a time.
First, your parents’ relationship: I have to believe that your father is aware of your mother’s infidelities. He stays in the marriage for his own reasons — probably reasons you either don’t know about or don’t agree with. You can’t change their relationship or your father’s decisions. Sadly, that means that you probably will never have a “healthy family life” with your family of origin. I’m glad that you can salvage a loving relationship with your father. Please do embrace that.
The way to the family life you want is to look forward, instead of back. At 22, you are old enough to leave your childhood home and to look for a loving partner who will help you build the kind of life you so desire. You can make the family with him and your children that you never had.
Which leads me to the history of abuse by your cousin. It is unusual but not unheard of for a mother to be in such denial or so wrapped up in her own needs that she can’t give her daughter the support she needs and deserves. It speaks to a lack in the mother, not the daughter. The fact that she continued to be unsupportive after you had an abortion only highlights how inadequate your mother has been to the task of mothering. It will only give you more pain if you try to change her.
You do have two parents. You didn’t mention whether your father knows of the abuse. If you feel it is safe to tell him, you may find support from him. If he cannot accept what happened to you, for reasons of culture or personality, and provide support for you, then you should probably not look for help from him either. But that does not leave you alone.
It’s a sad fact that there are thousands and thousands of women who have suffered as you have. The only good thing to be found in that is that those who are in recovery are often able to reach out and help their sisters in pain. Do look at the forums here on PsychCentral and see if you can find one where people share something like your experience. People on the forums offer each other amazing encouragement and support.
I also encourage you to find a therapist if you can to give you the individual attention and support you need and deserve. Look for a professional you can trust and who you can confide in to ask where you can get help for your trauma and depression. I don’t know enough about mental health services in your country to guide you. Perhaps your physician is a place to start.
I wish you well.