does it not seem weird that in the short amount of time you've been together you're already having to block things out? if it was right, you'd be accepting her past but like you say it's haunting you and eating away at you. it's not healthy in the long-run. IMO you shouldn't even be thinking to yourself about if she's gona cheat on you in the future either, makes it seem like you think it's gona happen at some point.
They called us a dead generation,
They told us that we wouldn't survive
They left us alone in the maelstrom
As you can see we're all clearly alive.