Hi confused, I read your post. There could be lots of reasons why this is happening in your life. Maybe you are bored, lonely, looking for validation, feeling down, restless. That is something that you can think about further.

I think at this point you are starting to get serious enough with this other person that you DO need to make a choice. So, let's examine the consequences of your possible courses of action. Off the top of my head:

1. cut all ties with my online crush?

PROS: You will not betray your marriage further. Could work on strengthening your family/marriage.
CONS: You will lose the feelings that you're experiencing right now.

2. Or explore it?

PROS: You get to experience the thrill and possibly fall in love / have passion.
CONS: Very likely to ruin your marriage. Might harm your relationship with your child, too.

3. Or act like it never happened, deny my feelings, maintain status quo?

PROS: temporarily end the betrayal
CONS: needs stay unmet, repressed feelings will come back stronger later

Are there other options you could add? Do you agree with the pros and cons listed above? Can you think of more?

I hope this helps.