Found used condom, proof of cheating?

Me and my boyfriend have been dating for quite a few months now, and we do not use condoms because I am on birth control which I know I still should use them. So the other day we had taken a shower together like we usually do because we are always together, probably too much sometimes, but after showering I happened to look down at the trash can when I was drying off and I saw a used condom in the trash. Again we don't use them and about a week or two ago we had broken up so we can just have our own space, his trash isn't that old either because I'm the one that usually cleans it up. And I asked him about it, he didn't seem to know where it came from but didn't seem that phased by it. If I found a used condom on my trash and had no clue where it came from I would freak out at my roommates but he didn't. So then I looked through the trash and found the wrapper which was a trojan for her pleasure which none of his roommates use. He claims it isn't his and has no idea where it came from and the last time I caught him in a lie he said he wouldn't ever lie to me again, but I'm sure that is a lie, because that's human nature. I know using a condom for masturbating is out of the question because he usually does it in the shower and he doesn't use condoms to do it. All of his roommates claim that it isn't theirs even though they always prank each other. And they claim that they haven't noticed any girls come over to his house when we were on a break but I am aware of bros before hoes, so that could also be a lie. So I am just curious to what you GUYS have to say about this and what you think the possibility is. because it seemed like whoevers condom it was, tried to hide it but obviously didn't do a very good job.
Found used condom, proof of cheating?
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