Am I paranoid about my relationship?

I will keep it short: I live with my boyfriend for about a year, recently I had to return to my hometown just for one day, and when I came back I noticed that the inflatable mattress we were sleeping on with my boyfriend for about two weeks is broken (the air was coming out of it slowly, so we wake up the next morning on almost flat mattress). I know it might sound ridiculous and I don't have any other evidence, but I was scared when I thought that it was maybe that my boyfriend cheated on me on it? I know how it sounds, but the mattress was just fine with both of us sleeping on it for two weeks and suddenly it was broken when I was away. However, recently my relationship is not going well and I often question my boyfriend as some time I caught him sending messages to some girl that were slightly flirty. From that moment I caught myself thinking about weird stuff: I know my boyfriend likes to do it in a rough way and I started to imagine that when I was away, he came back from his classes with someone and the mattress got broken from rough sex? Additionally, he mentioned to me that he is still studying with some girls with whom he had one-night stands and it's only his second longer relationship and we are pretty young, so maybe he is not ready to settle down with one girl?

I know it all sounds ridiculous, that such thoughts could even cross my mind, but I really hope for some advice, even if it might be rough to deal with these thoughts and how to learn to trust him again (because I lost some trust after earlier mentioned flirty messages), I'm really afraid that we might break up over small thing in some time, but in overall he is great boyfriend and I don't want to accuse him over nothing, but feel safe around him again. He claimed that there was no one in our apartment when I was gone and I didn't see any other evidence (female hair, also the sheets were the same as the other day). Sometimes I'm ashamed that I think about such things, but I was pretty badly cheated in previous relationship. I thought I healed before entering the new one, but something triggered my fears again: I'm probably most afraid that he might have cheated and now laughs behind my back/gets away with it, because I'm too naive, while I will be trying my best for him in this relationship.