Does he love his ex?

My boyfriend was with his ex for 3+ years. He loved her an awful lot. She cheated on him 5 times which he knows about. He took her back each time. 
She ended up leaving him. He went in to a pit of depression and has only recently came out of it. However, she recently gave birth too another mans baby. My boyfriend (before we were together) had offered too raise that baby with her. 
She gave birth in September 2015
And me and him started seeing one another October 2015 
I worry that he is only with me because he can't have her and that he loves her. He tells me about all the gifts he bought her, their sex life & how badly she treated him. 
Am I a mug?