Divorce after ILR

I have been in UK for 5 years and my ILR is likely to get approved next week (same-day application). I have applied for my son as ILR-dependent (he has been on a dependent visa since 3.5 years). My wife had her separate Tier-1 General Migrant visa and she has applied (postal application) for extension of the same. Her visa-extension is likely to get approved within the next 4 to 6 weeks.

I am now entering a complicated situation. My wife has just told me that she wants divorce from me. What do I need to do in terms of paperwork in UK to ensure that I can walk out of her life forever as soon as possible (in less than 1 month if at all possible) and my son will still be elgible to get UK citizenship after 12 months from now?