It would normally be sensible not to make any substantial capital commitment before finances are settled once for all within the context of a divorce. Indeed, if the other spouse heard of the plans they could be stopped by injunction. Bearing in mind that you are older than your wife, in rented accommodation, your wife has another partner and she wants all the equity in the matrimonial home it is quite reasonable that you might need to access your pension in order to buy a place to live.