Female Blog Reader's Man is still close with his ex

Hi Emeh, please help me post this cos I'm confused and I need to share my problems, thank you.

I've been dating this guy for a while and we've grown pretty serious very fast but thats not a problem because I love him. But there is this one thing that has bothered me since we started the relationship.

 I knew my boyfriend when he was still with his ex and he always told me great things about her, like he can't do without her, he's very sure she's the one as a matter of fact he was even going to propose to her this year then she broke up with him and she started dating someone else.
This left him heart broken as expected, at that time I too just left a relationship and I think we were both lonely so we became even closer friends and then not too long after, we started dating.

The problem now is he's still very close to his ex, she calls him constantly (let me add here that she's left the guy she was with cos he just wanted to sleep with her), she calls him to help her with stuff that in my own opinion any other friend can do but my bf doesn't see this has a problem, In fact there was this time she told him to leave me so he could help her with something, he didn't go but he made some calls and was able to get someone else to help but she refused, he's also lied about somethings that involves her. We've been fighting about this recently and he says i'm over reacting but I don't think I am.

 Please I need your honest advise, do you think it's not a big deal? Bearing in mind she has called 98% of the time I'm with him and I know they talk when I'm not there. He says he loves me I should let it go. Please what should I do?
I know he reads this blog and I'm hoping the comments will help us resolve our issues. Thank you.