Thanks for your response
I can only advsie on your circumstances but I can generically advsie that is this was NOT your ex wifes main residence when she sold it to you , then she will have a capital gain consideration. Bu you advsie it WAS her main residence so its just you that will have a capital gain consideration, based on what you advsie.
I advised on the basis that you said what happens if it was not your main residence - if it has been then you will have no capital gains as long as yous ell within 18 months of it ceasing to be your main residence,
If after 18 months, then you will have some exemption for the time that you lived there, plus up to 18 months after vacating the property and any gain left over will then be considered for capital gains.
The capital gains is based on market values, not what you may or may not pay
And you seem to asking for advsie on how to proceed, which we are not permitted to do - we can only provide information as per Just Answer rules.
If you die within 7 years or transferring assets then you will still be liable to Inheritance tax (although this tapers off the longer the time that has lapsed between the date of the gate being made)and if you continue to benefit from more of the rental income then it will not be treated as a transfer at all, unless you can be seen to have transferred the % of legal ownership to your son and also the rental income (and of course he will have to be over 18)
I have added a link here re gifts and the 7 year rule
Let me know if I can assist further