Will you die for sure if a Black widow bites you?

I've seen them outside in my yard, and now I am nervous that they might make their way into my house. i may sound paranoid, but now I feel like my life could be in jeopardy cause these things might crawl into my house, and bite me while I'm sleeping or something. I know people get spider bites while asleep. So if you get bit are you going to die, and will these things start coming in my house?