Please Advice!! I’m Pregnant But I Don’t Know If the Baby Belongs to My Husband or His friend

A woman has opened up about a shocking event in her life that may be about to ruin the good life she had enjoyed with her husband.
The unnamed woman revealed how the grave error she made is about to cost her her home.
Read below:
Please help me.

Some months ago, I made a most stupid mistake by sleeping with my husband's friend.
Things have got more complicated since then. Things too long to state here, and now I have found out I'm five months pregnant.
I was very shocked – I have a skinny physique and I'm not showing at all. I went to the doctor and they said it was too late for a termination.
Although I have been having regular sex with my husband, I am not sure he is the father. I feel that his friend may have been responsible for it.
I love my husband so much – he is my best friend as well as my lover.
I made one mistake in the 10 years we've been together – I'm just not that kind of girl.
It's almost like it wasn't me doing it and I feel so guilty.
My husband and I have been trying for two years for a baby and if this baby isn't his, it will destroy him.
His friend has no idea I'm pregnant and that it could be his.
I can't stand him – every time I bump into him he gives me that look of, 'Yep, I've had you!'
I don't want him to be the father – he would be a terrible dad. He already has kids he never sees.
I want to come clean but if I do my husband, my family and friends will turn against me.
Please give me some advice.