PLEASE HELP :( what should I do?

I’m hanging out with a guy tomorrow that I have only talked to over the phone this is the first time we are gonna hang out (at his house) and we have hinted at doing stuff before but today I started my period.... :( since it’s out first time with each other I’m not willing to have sex etc. on my period, if things get heated how do I tell him I’m on my period and don’t want to? I don’t want to disappoint him and don’t want things to get awkward if he thought we were going to. What if he’s just using me for sex? I don’t know what I should do but I really want to hang out.