Possibly pregnant

My husband and I had an accident last weekend where we had sex and he finished in the condom. Wiped himself off and put on another condom to go again. The condom slid off this time as he pulled out. He didn't come in the condom that time. The condom was stuck in me, the rim was on the outside of me though. I'm not on birth control because I hate how it makes me feel. Which is why we use condoms. My husband had a vasectomy at the end of January. He sent in his sample a week before this accident and heard back that he had a few sperm in his sample, but they were dead sperms, this was 2 days after the accident. I didn't get a plan b because we honestly didn't have the money for one and we both thought it was fine because bis vasectomy was 4 months ago. We figure he would be cleared of all sperm, we were wrong. He had sperm, granted they were dead but maybe they were alive when he done the sample and died on the way to the office (he mailed his sample). Well it's been a week since the accident and I've been cramping off and on for almost 3 days. My period is still a week away. Could I be pregnant? Could the cramps be implantation? We have a daughter but absolutely dont want anymore kids! Which is why he got the vasectomy. I dont know what to do. Help...