Unfortunately, cheating isn't one size fits all. Some people are good at hiding it, some people suck at it.
I've known people that have been cheated on and never suspected anything. Conversely, I've known people who were CONVINCED that their partner was cheating on them when they weren't.
The truth that a lot of people don't want to accept, because it means accepting that you can't control or even know for sure if someone is cheating on you is this- NO ONE can ever be 100% sure their partner isn't cheating on them. Unless you are with them 24/7, you just have to trust them, as they have to trust you. I would say if you discover a REASON not to trust them, that could be a sign of something going on. But these reasons can vary wildly and some could be suspicious and others, innocent. I once got suspicious of a BF "hiding things" but it turns out he was planning a surprise trip for me- so our instincts can sometimes be wrong, too. I've also known people that were just good at hiding their tracks and their partners would boast about having the "perfect spouse".
It really all boils down to trust. At the end of the day, that's all you really have. You either trust the person or you don't. If you do, there's no issue and if you don't- break up.
I'm going to approach this from a bit of a different place than others have.
I actually suggest that you do NOT "bury this". Wanting to reconnect with someone from our past doesn't always mean it's because we want to jump into bed with someone or ditch our spouse to be with them. You could potentially be throwing out a personal journey that could be important to your development. You flat out say you have no interest in leaving your current wife, so I think there is something here worth exploring as your desire to reconnect with this old ex.
People may reach out to exes for a variety of reasons. Sometimes people assume it's cause you want to get it on with them, which is kinda of assuming the worst of someone and not always true. Sometimes people reach out to make amends for past mistakes, to heal trauma, to apologize, or even just to reconnect as friends. I don't think it's playing with "fire" unless that's your intention going in or you think yourself unable to control yourself. I think as long as those two things are clear, comfortable and in your control, then my humble opinion is, one shouldn't deny themselves an opportunity for growth simply because others think you should never talk to an ex or to diminish every encounter as "it MUST be a sexual thing."
I think you should think about why this strong desire has arisen in you. Are you unhappy with perhaps some aspect of your marriage? You say you would never leave your wife, and even if it's true- could there be something that this other person represents something you don't feel is being fulfilled in your marriage? Or maybe it's NOTHING to do with your marriage at all, but about YOU.
You say you broke up due to your own personal issues. Perhaps some part of you wishes to atone for that. You could do that, simply by reaching out via email and saying you regret how you handled the past. Maybe it's simply because you would like her in your life as a friend. Everyone feels differently about this, for me personally, my opinion is that you should be able to trust your partner having friends of the opposite gender. They may provide meaning/support to your partner's life that they need. You should want your partner to have support and platonic love from other sources than you. (and if you don't, you likely have insecurity/control issues and view your spouse as property, which isn't healthy) If you don't trust your partner, why are you even with them? Because no one can ever be 100% sure their partner isn't cheating on them, unless you are with them 24/7- you either trust them or you don't. And again, if your assumption about them is they will instantly hop into bed with someone else, why are you even with them? if you don't trust that even if someone is flirting with them or even suggesting more, that they would confidently say NO, then again why are you with them?
But back to you, if you think you may want to be friends with this woman, I see nothing wrong in offering her friendly support. HOWEVER, if you are viewing this as you want to see if there is still "something there", then I do NOT recommend meeting with her or offering what you cannot give. BUT if this IS the case or you find yourself going there, ask yourself WHY. This is important. There could be something you are in denial about or internally struggling with that you just haven't identified. It may not even be about HER Per se, perhaps it could be wanting to be young again. Maybe, it's there is something you had personally as a kid, some aspect of yourself that you wish to reconnect with. Or possibly it's that you miss having a friendly connection that someone that meant a lot to you. As long as boundaries as clear, then I see no reason why you shouldn't have that friendship.
I can't tell you the reasons or your feelings. BUT- I personally do not think it wise to just "forget about it", as I do not think that's a healthy choice for you. I think it's important to explore our motivations and desires as a way to find insight into ourselves and look for growth opportunities. Assuming this is just a desire for an affair would be a disservice to you, your potential growth and frankly to your wife if there's something you do feel your marriage may need to survive and thrive.
Remember, issues we don't resolve only come back and can lead to worse mistakes if we don't address them head-on the first time. I think it's overall positive to figure out WHY you've been feeling this way. I disagree with denying your own thoughts and feelings for the comfort of others, that's just living a lie and will eventually come to a head anyway. You should be in a marriage and committed to your spouse because you WANT to be, not because you feel like you "have to". That isn't healthy for anyone in the long run.
GOOD LUCK.
