First of all congratulations on taking the plunge. I got out much earlier in life than you but it is never too late to leave the rat race behind...
I agree with others that online stuff is not going to give you the practical classroom tools and experience you'd get from an intensive face to face course. The CELTA, Trinity, and SIT TESOL are all options I would explore here.
I also agree that although a degree is a nice plus, your extensive business background can get you into teaching Business English, which can be a more lucrative field than standard English teaching. Being willing to wear a tie, and having a few years on the typical TESOL teacher, will also help give you the gravitas
needed to be successful in this niche.