Withdrawing contested divorce case and filing mutual divorce

Hi, I got married on 2014 and after my marriage it was revealed that my wife had an earlier relation and she was still continuing it after marriage. Luckily, I was able to collect few proof based on their conversation and accordingly filed a case for decree of divorce/nullity, as it was happened even less than a month and marriage was not consummated due to her unwillingness. During the six months before filing the case, they continuously harassed us by different means but didn't go too far perhaps because I had the proof. Once we filed the case, they contested the case(rather made it delayed) for more than one and half years either by not arriving in some date or bringing some technical points like you can't file a case before one year, this page is missing etc.. Now they have come up with a proposal to do a mutual divorce as this case may hamper their daughter's image and also both of us need to settle again etc.. As we also want the divorce and contested case will take a longer time, we agreed on that. We didn't take a single penny from them during marriage, only some dresses and few jewelries are there which her parents gave her and we informed that we will give them everything once the mutual process starts. But then they have said that they need all the proof against them once mutual divorce is started. I strictly said that I can give that only after getting the final decree. Now looking at their behavior for last two years, I'm now doubtful about their intentions and thinking how should we proceed. Please suggest what are the things I should look into if I want to go for a mutual divorce. Regards,