Pantys under his bed sheets 😔😤

So today after a beautiful night drinking and talking with who supposedly was my boyfriend who last night wanted something real serious with me and who for the first time told me that he loves me! I found a panty under his bed sheets when i was fixing the bed obviously there are not mines. Last night when i got to his house the bed was a real mess and there was clothes of his every where on the floor. He's trying to say that there are from a person from his past and that he didn't know he had them and that because of all the mess he had probably there were somewhere he didn't know about! i don't know what to think or do! should i believe him when the night before he didn't texted me at all. when first i found a lipstick on his car, then i saw a random woman texting him with hearts and kisses 😒 Should i really believe the story he's trying to tell me?