Vasectomy regret

My husband is 34 & I'm 36. We have 3 kids ages 5, 3, & 7 months. He was dead set on having no more children even though I tried to persuade him to give it some time and not to rush in to anything but he proceeded... long story short, he had his Vasectomy last month and immediately regretted it... as in the same day of the procedure! My periods are still not regular because I'm still nursing and they have been super super light. Theres no chance of me pregnant but Today he brought home a pregnancy because he wanted to know for sure. When the negative result came up he cried. He was so heartbroken. I didn't know what to say...