Possibly pregnant cat?

I'm new to this website, BUT I've been tryin to find answers to my question for the past 2 days and have found nothing. I think my female, Karma, Is pregnant. But my mom wont believe me because the male keeps tryin to mate with her..Karma has ballooned in sizes quite a bit, And her belly is a bit hard with her nipples bein a light pink an a bit plump. The male cat will mount her, then when she try's to run from him he grabs her by her throat and will either drag her, or shake back n fourth like a dog would in a fight..Yes I know it sounds weird but I promise it Is exactly what he does. My two questions are 1. Is she pregnant? and 2. Is he tryin to mate or kill the un-born kittens? I read somewhere online that a male will sometimes do this trying to kill the un-born kittens but I don't know. I really need help soon. Thanks.

If she has been mating with him she is probably pregnant.  He is continuing to try to mate as she might smell a bit 'that way' and/or he is sexually frustrated.

Both of them should be neutered ASAP.