My girlfriend is threatening me to commit suicide if I don't marry her

I had a relationship with a girl for more than 3 years. We had physical relationship many times. I promise her that if the relationship goes in a good track I will marry her.She is very possessive so I breakup with her.Now she says she can't live without me. If I leave her she will commit suicide. I almost sure that she may commit suicide because she don't have any good family background and any relatives. The only hope in her life was me. But I can't marry her. My financial and family background are very high.Can I face any legal problems if she commit suicide? She don't have any proofs to prove our relationship. But their is CCTV footage and identification details in hotels that we stayed together . We are from different religions.