The part that bothers me about your post is not that you're concerned that you cheated on your wife. it's that your wife's friend being pregnant and the prospects of having to deal with that are a bigger concern to you.

**amending my response**

I should have further elaborated my statement here. yes it's true that it seems that your original post didn't mention anything that was about how you stepped out on your spouse. So it brings to mind a few questions. I don't know if anyone can give any reasonable advice with the brief questions you posted.

You mentioned that you slept with your wife's friend and later mentioned a few times, but you have not stated as whether your wife knows, whether you want to fix that problem or if the pregnancy alone is what is bothering you.

Initially the way it's stated it makes me think that you're worried because your wife does not know of the adultery and she would or may find out due to the pregnancy.

So then the question remains what is your goal? Do you want to reconcile with your wife, do you want to patch your marriage, are you pursuing the friend, etc. What is your end goal because that would help to give people the information needed to advise you better.

if your wife does not know, that's first, if you want to keep your marriage, it needs to come out of the closet. Regardless of the consequences this has to happen. Worst case, she leaves you. Best case, you can find a way to move past it but you can't move past this without her knowing and your coming clean on it.

With the above having been taken care of the pregnancy itself will be a much easier thing to deal with since it won't be carrying the risk of being 'caught'. From there you can decide how you will deal with the pregnancy, your responsibilities, and the friend's choices going forward