Is he just using her??

My cousin has this family friend that’s her age and they’ve known each other for years but never really talked. Anyway, he added her on social media and started to talk to her. He started flirting and said all these years he’s liked her but was scared to say anything. Long story short, he has a gf but she’s abusive (hits him, verbal abuse, nags that he can’t do anything good) so he’s tired of it. He wants to start dating my cousin but doesn’t know how to leave his girl.
Recently, since yesterday morning he left my cousin on read and watches her stories but doesn’t talk to her. Was he just using her?