I feel your pain. The answer to why…you will never find out. The best i can say is because he can. He will continue dipping in at out is to have some control over you. When a similar situation happened to me i sought counselling and its simple. The more we continue to respond rhe more he will do it. People can be very selfish. They dont consiser the full impact of their actions. I allowed him to remain in my life by responding. One day i decided to stop. He reached out even more. I had to find an inner stregnth. It was really hard. He cried but after 11yrs i found my self worth.
Your daughter needs you and you can so this.