[kryptonite123]

You thought you strike toto when she gives in and have sex with you willingly.
Next thing she starts to extort money from you for example 20k

1i) Give her the money ------ She might ask for more and more in future; it might be a bottomless pit you have to fill.
1ii) Bargain with her - make it 5k ----- Same as 1i) but then again, was she really a willing party in the first place, or did you make any monetary promises? This one only you know.
1iii) Ignore her - She then threatens to tell your wife about it. ----- Like what littlepok said, depends on how your wife is related to her; if it’s a casual fling, then ignore her. Focus your energies on how you intend to apologise to your wife. If not, then you might have to consider 1ii).

2i) Tell her go ahead to tell your wife
2ii) Ignore her - She then threatens to make a police report against you for rape. ----- If she has sex with you on several occasions, how does that constitute as rape; the police is not stupid. You can countersue her for blackmail.

3i) Tell her go ahead and report
3ii) Ignore her further