He might be having an affair with his ex?

we have been so gud 2gether but now eish, i'm not even sure what to do,as much as i love my husband i won't stand him cheating n being an untrustworthy man,i suspect he is seeing his ex, i saw missed calls and a text msg, we talk about it n i was convinced nothing's going on, but now i don't seem to be that much understanding, what can i do? Am i crazy or what