Is my husband planning to kill me?

I feel really irrational asking this question-paranoid-but in the past my husband has put his arm around my throat picked me up by my hair but all of this after finding out I cheated on him. He recently had an emotional affair at work with a woman and isn't going back to the job but I viewed his work pc and in the search engine was "dismemberment". When I searched dismemberment myself all I could find were life insurance and bodily dismemberment. He says he doesn't remember looking it up and that if he did it was just to know how to dismember a group he started. When asked what group he did not know. He is a math teacher. I am constantly afraid to drink a drink he has prepared for me. I think he would rather me be dead. Can someone please help me. I don't want to overreact and at the same time I don't know what else to look for to determine whether our children and I are safe. Everyone thinks he's such a great guy-if anything goes wrong in our marriage-our extended families blame me and I take the blame. He has everyone believing he's just great (and he is most of the time). He was molested by a neighbor one time as a child and used to make little houses out of twigs and set them on fire-he blew up his GI Joe men and threw a fire bomb into someone's car. Is this normal? Please help.