Unless you had asked her about it and she had blatantly lied (even which can be understandable in certain circumstances), it shouldn't be an issue. Did she love you in the past? No. What's important is whether she is going to love you in the future. Similarly, what happened in her past, possibly before you were even in the picture (as her love) has no bearing to you.

I know our culture makes it hard for us to accept this fact easily, that feeling shall pass - but only you can do it. You have to convince yourself that her past doesn't matter.