Advice

Reasently I have been having a weird vibe from my boyfriend, he goes out frequently and dosent come home until late, it gets on my nerve. So I just found out that my boyfriend has been texting his ex girlfriend and they have talked about wanting to hangout, then doing some flirting... And when I'm not home (I've been visiting my family) he always text or messages random girls back saying they should hangout.. So where dose that put me? Am I really not that important, am I not doing something I should be? What do I do, it's been a reoccurring problem and for him he seems like there is no harm in 'just talking'... It just really makes me insecure and feel like crap, and I just don't know what to do. Any ideas on either how to handle this? Or advice in general on what to do? Honestly I am at a loss.