Dear Mr. Maspro
Love is a powerful emotion. It can PROPEL one to great heights of ambitions beyond one's imagination, or burn one's life to CINDERS, when not properly or PRAGMATICALLY managed...
Based upon your posts, you seemed like a decent Human. You have a wife & a child, & you did not mentioned any problems with them, but everyone knows life is never a bed of roses. There will be issues at home, but as you did not mentioned it, it probably means you are in control of it & bearing it as best as you can.
That you had decided to engage extra-marital sex shows that perhaps sadly in a way that you are only Human, like most male - which cat does not eat fish? It also sadly shows your mentality & desires which are not fulfilled, perhaps out of longings that your partner did not live up to?
It is only common, sometimes it seems taboo to talk about sexual desires in our straight laced society, but it would be better to talk, & listen, to communicate with each other & find compromises/solutions towards a better & more rewarding long relationship on a VOWED shared journey of life thru the sacred sanctity of marriage...
Vows made are sacred, a promise that must be kept. Only animals will break vows, comprehensible as they have no intelligence to understand what vows are, but they do have HONOR still such as even a dog will jump with joy when it meets you each day. Thus, how much more should we Humans whom are far more intelligent than animals, behave?
However, you still sought for companionship outside.. It's comprehensible as mentioned - which cat does not eat fish? It's only a mental issue, but it can be resolved, as you already have a 'fish' at home. It may seem fun, thrilling & exciting, to find new fish, but in the end, all fish are the same, once desires are satiated.
It is decent of you that you do not mind your ML's line of work. Most men do. ML too are only fellow Humans. Love is beyond the physical body a Human possesses. It goes far deep beyond the body & into the mind. Which is perhaps why she likes you, for understanding & liking her.
However, you made a vow to your present partner. It must be kept, more so as you have already a child born out of love between you both. The ML found you too late. You are already taken. Best to leave her & focus your energies & love to your family. They are a certainty & a longevity to future happiness, proven by many families - the building blocks of civilization since Humanity began.
End the intimacy with your ML, as such will only deepen the feelings of love & being loved, especially for her when you yourself admitted you are not in a position to go far in the journey of life with her. Be a friend instead, help her out as a friend would, give advice & suggestions, to find a better life, motivate & guide her along, not lead her on for your own selfish desires, & you would be respected for life as a fellow Human by her, far more than being cheated of her feelings for you.
All the best.