It would likely hurt you, not help. Jim Hacking and other lawyers explained why on multiple occasions.
First of all, this is your I-751 now and your ex should not be involved other than his sworn affidavit and evidence.
Secondly, there's been instances of US citizen spouses being intimidated into signing statements at USCIS accusing beneficiary of immigration fraud. Even if you ex is cooperative, he may be told by immigration officer that he could face jail time / huge fines unless he signs a statement agreeing that you weren't sincere when married him etc. Also IO, if really wants to deny you, can put you in different rooms and question for few hours about marriage. IO may ask such questions, that could puzzle you and your ex. If too many non matching answers are given you could be accused of fraud then. USCIS can actually reach out to your ex any time now, asking to write or sign statement that would hurt you.
That's why you need to get such sworn affidavit from your ex ASAP, before USCIS get to do it, if they're planning to. You may want to have a lawyer helping you writing a strong affidavit for your spouse and for you, highlighting the timeline of your relationship, how it developed, how you lived together married and what lead to breakup and divorce.
You may also want to have legal representaiton at your I-751 interview to ensure IO does not overstep the boundaries. They can also prepare you on mock interview for any possible questions and make sure you answer everything correctly, without volunteering any information or giving ambiguous responses.
Of course you can do it all on your own if you cannot or do not want to hire an attorney. But you need to read this forum a lot as well as watch YouTube videos about these situations and what to do.