Am i being jealous or am i just taking precautions?

My boyfriend and i have been dating for 9 months. He says he wants to marry me and i am pregnant with his child. he claims he hasn't ever loved anyone as much as he loves me. But he did have a first love. A girl hes known for 12 years and dated off and on many times. The last time was for a year and a half and was 6 months before us. He even raised her son with her. She wanted to remain in contact and he said he still wanted to be friends with her but didnt because i couldn't be comfortable with it. Should i get over it and let them be friends or do i have a right to not want him involved in any way with her. My fear is that he's loved her a long time and maybe he will rekindle some kind of relationship with her.