How to check the last time apps are being used?

On android, i check on the google play app the library. Is there any other way? I found a this (💙) icon on the recently used ones. I ask because an ex-employee uses that now for everything because she having a boy. That icon shows on my husband recently used ones but he did not sent that to me. Also last night showed the last time used the text message was at 12midnight, he got back at 12:30midnight but he did not texted me at 12m. She posted something like nobody keeps a better secret than a n*** with a baby on the way?? What can that mean? I say this because lovely husband is always in the bathroom between 1am-3am, thats when she posting stuff. It all comes back to a text she sent my husband saying she couldnt work because she didnt feel good & the other text was OH YEAH & IM EXPECTING, HIS REPLY WAS PK CONGRATS. Its just odd Can we say RED FLAGS!!!!??? I might be paranoid but im so defensive now. She crossed the line when she used to work there, him being one of the owners.