Royal Flush
Take some time, do some homework and then make your decision. Go to human services website if you have kids and use the calculator to work out how much child support you may have to pay, while there is no "alimony" here there is "spouse maintenance" which they can apply for (usually after the financials are settled) and you'll have to pay her.
Ultimately...you have to be selfish and go with whatever decision MAKES YOU HAPPY.
Did anyone see a program on SBS about Germany's lucrative sex business? A few WLs working at the largest brothel called Paradise were interviewed. One young gorgeous looking blonde WL was asked how many guys she had slept with and she mentioned 16 with whom she had proper relationships. Then the reporter asked how many customers she had sex with and at first she didn't want to say but when pressured she indicated over 15,000! OMG! If she had slept with over 15,000 guys, would you date her?
That's the right way to think because you're trying to figure out the repercussions of each option.
For me, a major major reason I took option 3 was because my ex-wife is the same age as me. Option 2 was out of the question because I know myself, punting and infidelity runs through my blood. If I took option 1, there was a big risk that we would still end up divorcing after many years of deceit. If that happened, she would be left with no way of recovering, no way to find a better life. I did not want that to happen. So, I decided on option 3 when she was in her early 30s. She is now reasonably happily remarried and doing quite well.
I have no regrets at all about choosing option 3. You may think that choosing this option is to be selfish. It is actually the worst option for you because you will be in a bad shape financially, depending on your situation. You also may want to consider if your wife is already too old to move on if you left her, but only if you care about her wellbeing.
Whichever choice you take, never choose it because of your current girlfriend. GFs come and go, don't make life decisions based on them.