I totally sympathise, but Pgletion is right, you must leave.
Everyone is ultimately responsible for themselves.
If the worst thing happened, and your ex-partner took her life, then you would have to tell yourself that you were not to blame - and believe it. No-one can be held to ransom in a dead relationship in this way.
It sounds like your partner is manipulating you, and you ned to move on for both your sakes, so you can both learn to love again for the right reasons.
If you say you are going, and she says she will kill herself, tell her that you would be very sad, but that is her choice to make, and not a reason to keep you there with her.
Be strong - you'll be glad you did, and the chances are, in the end, so will she.