I don't think magic would be the best solution to this but I could be wrong I am only a high school student, but my thoughts on it is that he might not want to stay but if you were married for 16 years then try talking to him maybe you two can try to work things out, I see magic as a last resort to my problems but that's just me
I'm not very skilled but in order to find out, I think the best way of determining if someone is cursed is for them to lay down in a completely pitch black room and attempt astral travel, before they leave the body they need to physically open their eyes, they will see a pendulum above their head and if it's moving then something is wrong and if it's still then they are entirely of free will, I don't know much of what you could do, I don't use magic to get people to like me or to break up a couple, I only use it as a last resort and I feel like this is yours, you would have to ask someone else I'm trying to be able to see my aura currently and I can do very simple magic but I haven't even been able to astral project yet either, if someone else, someone more skilled could help you that would be better than anything I could do I wish you the best of luck though
I am extremely late but this is also for the person above and you as well.
She cannot manipulate your ex-husband under her control, even if she tried to do a spell it was his free will to leave you. You simply can't break two people up with a spell. Again, they will only do it with free will. If you are looking for a spell to do at all, you can do a honey jar to sweeten him for you.
well there are several options for you, but you won't like them.
first and foremost i would try and do some reflection on your relationship. it's hard and in an emotional state it's almost impossible for someone to have a non-bias look [so try and seek a counselor, talk to friends/family for their honest opinion, or an unbias third party] even the closest of relationships need work, sometimes you get too focused on you, or perhaps you've overlooked issues, perhaps you did nothing wrong and he just changed [people are always changing] so to prevent reliving the past it is wise to reflect and find a lesson from this tragedy.
spell wise you could try a honey jar to sweeten him to you once again, a love spell to bring him back, a banishing on her, a binding on him. many options depending on what you desire, but i recommend not doing anything too rash. be careful what you wish for, casting fueled by emotion can add great power to your spell, but its also the most likely to bring regret down the road. [if you still want a spell, i'll provide a link to one i posted]
once you manage to get back together, i insist you work on things together, reflect on your relationship, talk to a professional, and find what it is you both want. even if it turns out to be divorce, temporary separation, or renewed vows, you need to work on your relationship together, and as an individual. if you don't get back together, you should take time to heal, but still reflect. this might seem like a disaster, but it could be an opportunity for greater things. appreciate all the good that has come from your life together, while painful, it came with good and bad. good luck to you.