Just randomly checked my SO email and found out that he recently exchanged emails with some lady he used to work with and with whom he was friends with benefits. I think what irritates me the most is the fact that he initiated the conversation by saying " hey what's up". Then as the conversation progressed - he asked the lady what's been up with her , to which she responded " life has been hard without u especially as u stoped taking care of me- lol" . Then my SO responded " awww I guess u miss me huh" and she responded back with  "Lol" then the conversation ends there for a while - then she comes back to say " how have u been "  - my SO didn't reply then went ahead to delete all the email conversation. Then he called me on FaceTime and we talked all evening and then he went to sleep . I constantly checked his emails to see if the conversation continued but I guess it ended there. ( I checked past emails and apparently my SO and this lady communicate only by email - I think she is in a relationship or something- not sure ) but that's how I found out they were friends with benefits - my SO had terminated what they had coz she fell in love with my SO and wanted more thsn just casual sex I guess but my SO told her in the email that " that's not the arrangement we had- I told u I was "freelancing" "And she had responded that she knew my SO didn't want to be with her coz of her kids. However all this happened before I met my SO. I really just feel hurt that he reached out to her. Why would he do that ? I know he loves me and wouldn't do anything to hurt me. But why will a married man suddenly reach out to an old fling? Should I ask him about it or ignore it? I am confused as I really don't want him to destroy the trust I have in him.