7 Years in Relationship. Is he cheating?

Today I found out that my bf has been texting this girl through text, flirtatiously, for probably 6 months as he admitted himself. In their conversation, I noticed the girl was just ranting her ex, and my bf was actually flirting with her, calling her “hot” and saying things like he’s “horny”. He said it’s nothing considering cheating if he’s not physically flirting with her in person, it was all online and that they’d probably never meet due to the fact that she lives across the globe.

I also noticed he downloaded all the chatting/dating/video call apps all at once a couple years ago. But the messages on some of the apps towards other women were January of this year. It includes him asking for sensitive pictures.

He said he doesn’t know why he does it and it’s not to intentionally hurt me. He just felt lonely and that he doesn’t have any romantic feelings for them.

I have had many issues when it comes to trust in relationships from trauma of the past. But I’ve grown to trust him more and I’ve never felt so secure in regards to our relationship this year.

I’ve been in a roller coaster of emotions. Feeling shook, confused, and hurt. Please let me know what I should do…he was the best I’ve ever had and I want to believe him in not doing that anymore but idk at this point. Please help!