This forum is a judgement-free zone, you won't get snide remarks (and that goes whether the sex was consensual or not). But I do suggest, did you report the rape to the police? Doing so can help a woman heal from the trauma and take her power back. I realize these things are complex, but please do consider filing a report if you haven't, even if you think it might devolve into a "he said/she said" and don't think the police will do anything. Others might be in the same position now or later with this guy, and your testimony will be in the record. If this is too much, one thing other women have done is post the story online anonymously, with the guy's name clearly spelled out. A word search can then find it, if women are looking.
Anyway, about your dates. Did you get "8 weeks 1 day" on June 14 from an ultrasound? While an ultrasound is not an infallible way to guarantee that the sex on May 1 produced the baby, it does suggest it. You could get a prenatal DNA test now, if you have the enormous funds it takes, or you can get one at the hospital when the baby is born for about a tenth of the cost (of a prenatal test), to confirm. Are you able to tell the guy from the 1st what happened on the 6th? If so, he would certainly understand why you want a test.
Even if you didn't have a question in your mind about which guy is the father, your baby should have a DNA test in his or her medical record, since the baby has legal rights to support from the father. (Only if you are married does the law automatically assume your husband is the dad, otherwise you need to put together proof.) It's a good idea to get that squared away as soon as the baby is born. Tell the first guy that you need to protect the baby's rights and want to do a DNA test when you're all at the hospital when the baby is born. Your doctor can tell you how to get it done, or call the courts in your area of jurisdiction that do family law, and ask the judge's clerk for the name of the lab or the process for getting a test. Witness the guy doing the swab and handing it in at the lab, so there is never any question that he did it and didn't send a buddy in his place.
I'm sorry you're going through this. Congratulations on the upcoming birth of your little one. No matter how they start, babies are a miracle. I wish you well.