If you had a full-blown affair in the past and have had this infatuation now, I think you need to work a little more on affair-proofing your marriage. The first step towards that is taking a look at yourself and asking what it is you were getting (or thought you were getting) from these affairs.
Do you just like flirting and deep down believe you should be free to have a marriage of convenience, sex and affection while also having less significant relationships with other women? There's nothing wrong with that POV - provided your DW is on board with it. If you think this is you, own it. Tell your DW what you want and be prepared to divorce if she doesn't agree to it.
If you don't think that but you're 'weak', it comes down to taking responsibility for managing your life so that you don't ever get in a situation where an affair of any kind is possible. So no female friendships other than on the most casual basis, with complete transparency for your DW, etc.
Or you can look at your character flaws and try to overcome them, which will make you less susceptible. The attraction with most affairs is that the people conducting them feel more desirable, energetic, needed or alive than they have done in years. What they don't realise is that it is not the other person who is making them feel like that; it is the change from their normal life.
IME the main reason people fall prey to an affair is general life dissatisfaction - the job is boring, marriage has fallen into a rut although there are no real problems, you feel like you've lost your youth and identity under a mountain of responsibilities and far too little fun. It is easier to be flattered by the attentions of someone else, and to start with it all seems harmless enough and intentions probably are innocent.
However, unless you are very wary, it's very easy to end up putting all your focus on that other person, and by ignoring the other problems, they temporarily recede. So it's rewarding. Life feels better. So far, so good. And still you may not have exchanged anything other than a conversation, so no harm done, right?
Except it can't go on for too long before the spouse pulls you back to reality. Guilt then sets in, but it quickly transforms into irritation at being interrupted. Then what normally happens is that the person has to justify their actions, so they big up everything that is wrong with their marriage and sometimes even manufacture a few problems out of thin air. That's when things tend to cross the line into a full-blown affair, because it's almost justified in the head of the adulterous spouse.
Ironically, though, it may well have been a boring job and lack of outside interests that were behind the general life dissatisfaction; not anything wrong with the marriage. That's why so many affairs fizzle out - the respite is only temporary before dissatisfaction again rears its head.
If you take the time to examine your feelings, and work out why you need more stimulation in your daily life, it's much more productive. Changing your job, taking up a new, exciting hobby, insisting your DW spends an evening having a date night with you to keep the romance alive - all these things tend to have a much better payoff than an affair.
If it turns out that your marriage IS lacking, you can choose to work on it or leave - but that's a hell of a lot easier without the addition of a third party.