PLEASE ADVISE!!! I Told Him Not to Release Inside Me

 I am Pregnant for my young sister's husband. I travelled to Lagos to buy clothes for my shop about two months ago and had to spend a few days in my sister’s place.
I called her but her number wasn’t going so when I got to Lagos I contacted her husband who told me that she went to Ogun State on official assignment.
He agreed that I should come over and do my transaction from their house.It was raining when I got there so I got socked, especially while trying to get their keys from a neighbour.
They live in a one-bedroom apartment, so I had to go inside the room to change. I was really cold and was already wishing I had a man I could visit in Lagos when the unexpected happened.

Due to the rain my sister’s husband came in through a back door from the kitchen straight into the bedroom and I was completely nude; I couldn’t even bend down to pick my clothes.
I was just standing there motionless until he grabbed me and, yes, we did it.
We didn’t feel any guilt, just laughed about it and I prepared food. We both ate, slept together and had sex all night with each other. The sequence continued for the three days I spent in Lagos but after the first time we agreed he shouldn't release his sperm inside me.

Am now back to Enugu where I do my business, but unfortunately I am six weeks pregnant. No man friend, no boyfriend, no sex mate…. So who will I give this pregnancy to?
My sister’s marriage is less than a year and I just cant mention this to her husband.

The options I have thought of is either to kill myself or have an abortion. Is there any other way out of this mess I have gotten myself into?

Please I need HELP, and I need it fast! What should I do?