I agree with Passion4Sci. It's not a good thing, but it won't be impossible for you to get into pharmacy school. I remember for some supplemental applications, they allow you to write an essay on explaining problems with the law or other negative marks on your academic record. I would definitely call pharmacy schools and talk to them directly about this issue.
I also agree with him ....especially that more details are needed to assess the situation. Although from the OP's post, it sounds like the OP has accepted it, and thus, they probably did participate in some form of major cheating (ie. not a minor infraction blown out of proportion). because if it was minor, then I feel the OP's post would be more panic-y and defensive and OMG I GOT MARKED FOR CHEATING WHEN I DIDN'T REALLY ACTUALLY CHEAT - AM I SCREWED FOR PHARM SCHOOL? WHAT CAN I DO? ..... but maybe I'm reading too much into it.
I'm not sure what can be really explained about cheating. I got desperate? I had 5 other exams that day? I had a mental breakdown? There are NO explanations for cheating in my head that make it acceptable - any explanation (/excuses) you have, that I can think of at least, just show that you're not capable of dealing with the curriculum of pharm school. Maybe I'm being harsh, but I'm just saying what's on my mind - and I doubt any admissions committee will see it any less harshly. They'll probably think worse of it, as in the scientific community, any sign of dishonesty such as cheating is a career killer.
Is this mark on your permanent record? I know that at my school, if it is only the first time for you, they will put it on your school record and expel you the second time (and it is on your permanent record), but if you do not do it again, then when you graduate, all records of the cheating are gone. You should know precisely how you were "marked," as it can be a big difference.
Still, the best you can do is try to put a positive spin on it, and show what you learned. I think it's best not to put excuses to the cheating unless you have a SUPER DUPER GREAT excuse for the cheating. Just own up to your actions - your records say you did it, and any weedling and whining on your supplemental applications that it wasn't your fault or that you didn't deserve it will probably be looked on negatively as if this was true.... then it wouldn't be on your record. Be mature - own up to it, and then stress the positive things learned from this negative experience. That you learned cheating is not the answer, no matter what the excruciating circumstances of the situation, and that you learned how to cope with the stress that made you turn to cheating. Stress on the aftermath and the learning part - don't focus on the cheating part. You don't want to keep reminding them that you cheated, you want the admissions committee to remember that you learned from this experience. That's how I would go about it if this was me.