Slight mistake

I'm divorced, no children and at 42 successful career wise, last Halloween I met my sister-in-law 37. She was my late younger brother's wife. He died of cancer 2019 and she was out with her 2 children. I live in another city and was visiting my mother (widow) as I was in town for business and a business dinner, I was trying to find a way of skipping it. My sister-in-law dropped by to see my mother with her children. I'd just mention about skipping the dinner, mainly because I'd no partner to accompany me. My mother knowing her daughter-in-law didn't date or have much of a social life either. Suggested I take my sister-in-law to the dinner, caught off guard all I could do was say I wouldn't want to impose. My sister-in-law (SIL)said she would be happy to go with me. As it was Thursday, and the dinner was on Friday night. My mother said her grandchildren could stay overnight with her, so we didn't have to rush it. I decided to accept the offer and attend the dinner with my SIL we had a great time and partied a little too much. Sleeping together at her home and fucking again in the morning. Just a mutual lust occurrence you could say, one slight mistake I took no precautions and my SIL wasn't protected herself. Now she is pregnant to me, my mother is very happy, and I must say I'm happy also. My SIL is soon to be my wife and I'm relocating to be with her early next month. Marrying her and moving in with her and her children.