Reposting because I'm desperate for advice ASAP

So this is a very messy situation, but I'll try to sum it up. I have a boyfriend that my mom doesn't know about solely because she's the type of mother who would whack me over the head for looking in my SO's general direction, and, well, me and my bf have been doing a lot more than that premarital eye contact shit.

My mom found a condom wrapper, she told me she needed to talk with me about something she found in our spare room and I have no doubt it was a condom wrapper. I have time before we actually talk, but there's no way in hell I'm going to tell my mom I'm sexually active because that may be a (quite literal) death sentence. I don't really know what to say or do in thia situation. My current lie is a really stupid one- that he was using it as a pouch for change when we went to Rite-Aid as a joke (he's kind of a chaotic guy so it makes a bit of sense, plus it's a magnum so it kinda checks out???). I feel like she's gonna see through it, however, and I'm not really sure what to do. I'm actually having a panic attack over this shit, does anyone have any advice?

Update: ended up basically telling her that they must have fallen out of his bag when he was looking for a USB (there's a lot more context to that excuse), she luckily bought it. She ended up telling me she was planning on grounding me until I got accepted into a college (and I'm 17 without my GED yet), wouldn't allow me to see him ever again, and would start forcing me to go back to church. Luckily everything blew over, very terrifying moment but all is well. Thank you all for the support! Much love <3