Issues After Citizenship: Marital Status on Naturalization Certificate

I am naturalized USA citizen and i got my citizenship 8 years ago. During the naturalization process i filled up N400 form and mentioned that i was married to foreign spouse. However i was actually engaged during that time and was not married on papers. On interview/oath ceremony day the interview officer did not question me whether or not i was married because my naturalization application was based on the green card that i obtained through relative (i.e. my aunt who sponsored me). While it may sound that i am playing games but i am not. After i earned my naturalization certificate the girl that i loved got married with someone else and we moved on with each others life. Now after 8 years i want to marry someone who is in foreign country but if i file for her petition (Form - I-130) my naturalization certificate would state that i was married. The tricky part is that i don't have foreign marriage certificate to prove that i was married and apply for divorce. My only concern is what if i file I-130 would USCIS question about my previous marital status ? If yes, then is there anyway to amend my naturalization certificate. I know whoever would read this thread of mine would think that i am playing game and they would not buy my story but i swear on my loved ones i am not lying and whatever i did was an honest mistake. The only proof that i currently have is the photograph proof of my ex-girlfriend that she married someone else. I would appreciate if someone can guide me on what should i do now ?

Issues After Citizenship: Marital Status on Naturalization Certificate