The more time I had to ponder your predictament, I realized more needs to be said. If you're looking for a way out of telling the father/partner that he might not be the father--it's impossible. He deserves to know this baby might not be his. The other guy also has to be given the opportunity to know he might be a father. Since you are not married both guys have the responsibility of owning up to their actions and deciding their role. You don't want to wonder after this child is born who the father really is. And the baby deserves to know who her/his daddy is.

This is the time when YOU have to own your actions. This is the product of your actions and you must take responsibility for them. This is why I believe so firmly that sex is meant for ADULTS in a MARRIAGE. When the possibility of being pregnant is joyous and awesome, not a dilemma of wondering who the father is. Suck it up, tell both daddy-possibilities and concentrate on the miracle inside you.