You might try having sex in the woman on top position so that you can control the penetration. And before trying again, you might take several days – even as long as a week – off of sex to give your body time to heal. Perhaps your vaginal entrance has not had time to heal and so it keeps tearing again in the same place.
Often, men find that if they keep the cut clean, apply an over the counter antibiotic cream and avoid further irritation from partner sex or masturbation, that it will heal on its own within a week or two.
There are many different reasons why a woman may experience chronic genital pain. Some women may have skin sensitivities or allergies that cause the genital skin to become easily irritated in response to chemicals in laundry detergent, bath wash, soap, lubricants, or condoms.