MF1 got it in a nutshell. Adultery will make no pleadings towards your case. But once your both willing to separate, its just the situation of dealing with all, or any assets to quibble about. The house, and maintenance etc. It would be best, if ye're still on amicable terms to try sit down and speak about such isses and try and get a Deed of Separation in place asap. Costs are inflated by the length of time it takes to come to an agreement, so the quicker ye agree, the less the costs, for both of you.
Best of luck.