Desperatly need the truth?

Hello Im a 42 yr woman trying to find out if my girlfriend is cheating on me.Last night I asked a ??? about my girlfriend who say's she is in a rehab ,I dont believe that she is,Iam her 1st.gay relationship while she is going through a divorce please I know.I asked her to marry me , I spent 2000. on the ring .she pawned it when I asked her to leave due to her drinking and finding out she ****** a guy w/n 24 hr. of leaving me.I treated her like gold.Im n co. right now she is in mi.I asked her to change her pic .from herself toour sailboat if she really wanted to still be w/ me.Now is it possible for her to change it for only me to see meaning me (SAILBOAT) others (HER PICTURE) I do have a friends e-mail address and pword but I dont know how to get on her facebook account w/ it.Please help me w/ this,should i put my girlfriends e-mail on here so some one can check for me? im@ mat.vela@ yahoo.com if n e one can help thanks