I Had Unsafe Sex After 10days With My Wife From

I had unsafe sex after 10days with my wife from my travel back. That day is 8th day of her period. I failed to remove my sperm. We had 3 continuous unsafe sex but I did for sperm produce outside. But now we had worries of havinf pregnancy. We already have 2 children, aged 16 and over 10. and we already aged around 50. Pls guide for not having pregnancy. Thanks in advance.