I won't go too much into cursed objects here, but I will touch on a few things. Generally speaking, cursed objects bring misfortune to those around them. This includes the owner of said object. These objects have long, sorted histories and tend to have a lot of negativity associated with them, even death in extreme cases.
Some of the most well known include: The Annabelle Doll, The Hands Resist Him Painting, The Anguished Man Painting, and the Busby Stoop Chair just to name a few. These are all documented cases of cursed objects that have been investigated by paranormal and para-psychological groups, and some even covered in news reports and interviews.
Now, cases of these tend to be rare, but it does occur. However, that said, I don't think the object you have is cursed.
In reference to crystals, It is a common belief that crystals and gems vibrate with their own, natural energies. They are believed to be able to store it, channel it, and balance it. Unfortunately, they can do this with both positive and negative energy so it helps if you clean your crystals regularly.
They can absorb the energy of their environment, including emotional energy, so there is a possibility that the crystal has absorbed a portion of what you have manifested and generated in times of emotional distress. However, I do not think this alone caused the issues you described.
I would suggest cleansing the crystal before wearing it, if it has been some time since you've done so (if at all.)
There is also a sociological concept, first proposed by W.I. Thomas that I would like to touch on as well, since it correlates to what Madam has mentioned. It states:''If you believe things are real, they are real in consequences.''
Which simply means, our thoughts and beliefs can have an impact on our perception of events. You think the object is cursed and thus look for events and situations that make it so.
There are two possibilities here:
1. The crystal has nothing to do with the events, but because you believe it to be cursed, you see manifestations of that in your environment when you wear it. A serious of coincidental, and unfortunate, events, if you will.
2. You have put so much energy out into the universe, and emotionally fueled it in regards to these people (and it was then amplified by the crystal)that it eventually manifests and makes subtle changes in the environment.
There are several cases and reports of cursed objects, but the occurrence of it in history is a rarity, if we look at the number recorded over the years. It takes a lot of energy to put out that kind of energy, and more so to continually fuel it for an extended period of time, in which it would have a lasting impact.
Some of these cases are not cursed in the sense we think of. It was more of a spiritual attachment to the items that led to the events surrounding them.
Long story short, no I do not think your crystal is cursed. I would suggest cleansing it and using it in your practices, if you still wish to use and wear it.
Resources & Further Reading:
allietheiss.com/easy-crystal-magick/
www.spellsandmagic.com/Crystals.html
www.neatstuff.net/avalon/texts/know-how.html
The Crystal Bible ~ Judy Hall
Crystal Healing ~ Judy Hall
http://www.asanet.org/william-i-thomas
https://brocku.ca/MeadProject/Thomas/Thomas_Remembrances.html