Okay, so if I were in this situation, I would have to know a little more about the science of it to know what to do other than cry.
According to this case study it is possible to conceive via in vitro fertilization. Its comment about being allergic to her husband’s seminal plasma proteins means proteins in the ejaculate, not the sperm. So even with a vasectomy, you’d still have a reaction. It is possible to attempt a scientist/doctor aided insemination with pure sperm and not all the other fluid shot up into you but it’s a gamble.
(When you have sex normally, there are tons of things going on to attempt to help sperm get up there in addition to making it difficult for them. For example, your uterus has a “flow” of sorts that helps fluids move up into it. It’s not completely explained but it’s the same reason why women can get pregnant even it they’re on top. So, the turkey baster of sperm is chancy if only because I believe (I didn’t completely pay attention in class on this one) sex drives that. All the hormone release and what not. So if you’re in a cold doctor’s office and they just inject some into you, it’s even less likely to work than if you just had sex with your man.)
Anyway, according to this article and a couple others on PubMed, it is possible to desensitize your immune system but it requires sex every 48–72 hours. After the first couple uncomfortable ones, your immune system begins to develop a tolerance, but if you mess up, it can come back. You can also try to take some anti-allergy drugs with varied effect. The information on this “desensitization” method does not indicate if it would alter your sex in any other way.
In the end, I think for sex, I’d have condoms and if I really wanted to get pregnant, try the desensitization for a year (with that much sex, should help your odds on baby anyway) and if that didn’t work either adopt or go in vitro.
And if it’s the problem with seminal protein, it is possible to be allergic to all men, depending on what part of the protein is setting off your allergy. Scary.