Some things are better left unsaid.
Does anyone tell the truth on this one? We'll never know. Guys lie, girls lie, it's really nobody's business but your own. Whatever the number, he'll think about it more than he should. You're with him, so anyone before him shouldn't matter - to either of you.
How good your ex was at giving head
Ok, so he might need to improve on some things physically. Pretty much the worst way you can help him is to compare his skills with an ex's. 'What my ex used to do was....' no, no, no, NO! Erection dead.
The fact that you cheated on your ex
Howiye trust issues. Your current boyfriend should never know this, it was a mistake, you did it because something was missing in the relationship or you were just hammered and reckless. Whatever the reason, all he'll hear is 'I'm an untrustworthy horny bitch' and he won't forget it.
That you suffer from really heavy periods
Periods are a big part of a woman's life, 12 a year, around 450 in a life time. It's a shit reality that we all have to deal with every month, we got the short end of the stick, the raw deal, we really got fucked by mother nature... but he does not need to suffer as well. No matter how mature a man is, he will feel uncomfortable talking about your period and not only that, he will be in no way helpful. In fact, it's possible that you will get into an argument because of how painfully unhelpful he is. Talk to your Mum, sister, friend... just not him.
That one of his friend is hot
Not fair. He will imagine you and him having sex instantly. Nothing good will come of it, he will not get jealous in a cute way and tell you he loves you even more now. He will hate when you're in a room together and probably accuse you of flirting when you ask him to pass the ice.
That his penis is a 'nice' size and that big ones in the past have hurt
Oh dear. Men are weird about their penises, they don't want to think about another man's that has been inside you. It's simple, you wouldn't want him saying that your vagina is 'different' to other womens but he still likes it... WHAT DO YOU MEAN 'DIFFERENT'?
That you got come on to by 6 different guys last night
Whether it's true or not, your boyfriend will be painfully aware of what a ride you are. When you go out on the piss without him, he'll know what guys think when they look at you, it's exactly what he thought when he first saw you. You don't need to remind him that you're hot property, it will only make him question how you conduct yourself when you're out which is unnecessary.
That his friends are assholes
His friends might be assholes, but they are his friends. You have no idea what kind of history they have and sometimes the biggest dick can turn out to be the most loyal out of them all. Regardless, grin and bare them, they're not going anywhere and their opinion of you counts for something so play nice.
That you dislike his Mother
Even if he has an old bitch about her, under no circumstances can you refer to her as an old bitch. Ever. Boys' relationships with their Mums is sacred... back away.