I'm sorry about your fiance. All I can say that suicide is not the way to go. Although you feel that you have lost the love of your life, you may be the love of someone else's life in the future. As we never know what the future holds, things often happen in ways to prepare us for what our true life's purpose is. Whether we are to be wives or mothers, or single people, we are all here for a reason. I know that the pain you are going through right now is real and if you ever feel desperate again, I advise you to get professional help, aka suicide prevention, counseling, etc.
Now regarding the curse...whether a curse has been put upon you is really not important. If you believe there was a curse put upon you, know that whomever did it will get what they deserve in the end, if any maliciousness was intended. Also, if this man was meant to be with you, he will be with you. Don't worry about looking for spells to rectify the situation. What this all comes down to is YOU....not bending anyone's else will or cancelling out a curse, or getting even with someone. This is about you, your self worth, your self-esteem, your mental and spiritual state of mind.
The important thing is that you start to heal and mend your heart. Cry if you have to cry, talk to friends, family, someone, visit your religious leader (priest, pastor, etc.) Do what you have to do to get through this. Be brave and strong and know that you have a lot to offer in this world.
Although this is only my belief....know that you are not alone in this and that you are surrounded by love that is just beyond the veil.....