It does complicates things a bit.
If Guy1 ejaculated before having intercourse with you, there could have been enough semen and sperm in his fluids to make you pregnant.
If Guy1 ejaculated inside the other female and Guy2 had his penis inside her after Guy2 and then had intercourse with you, he could also have transferred Guy1's semen into you.
To give you an idea of the strange things that can happen: A woman gave birth to a black baby. They had no history of mixed race babies in either family. It turned out that her partner visited a prostitute that had sex with black guy just before her partner. Her partner transferred the black guy's semen to her and it got her pregnant. This is obviously a freak occurrence, but it shows you what is possible in these sorts of situations.
Since Guy2 ejaculated so many times inside you during your fertile week, he is however still the most likely father of your baby. You will however need a DNA test to confirm it.
Take care and best of luck for the last month and a bit, and the birth!