Sorry To be rude, but from what you've said, you have understood time travel all wrong(at least from what I understand). The theories I've read need a singularity. Not really a black-hole, but a singularity without an event horizon. The event horizon would keep you from getting to the singularity. A singularity has space-time all messed up in one spot. When you would travel through time, you would not be accelerating or slowing, but changing through different time frames(similar to what happens during frame-dragging to gas around a spinning black-hole).

By the way, I don't believe in time travel in the same sense it is described in movies; that is, i don't think someone can change my past. There are some theories that if time travel is possible, what would change would be another whole, i guess, universe would begin with the changes made during the travel.