Is my boyfriend too jealous?

We’re both 24. I don’t know how to word this as there’s a lot more to it than I can really describe if that makes sense. Anyway, I think my boyfriend is really jealous and he thinks I’m really distrustful. He always brings up how I’ve “lied to him so many times”. One time he brings up is when I went to a male friends house to see his new place he had just bought and renovated himself. Apparently I’m a liar because he was under the impression that I was there with loads of other people when in reality it was just me and my male friend. For some reason this makes me a liar? Also, he continually asked me questions about a night where I had a guy round to my house BEFORE I was in a relationship with my boyfriend. We were just casually dating at this point and we were both seeing other people as we were NOT official. Anyway, I told him that we didn’t sleep together because we DIDN’T. Eventually after him pushing and pushing and asking about it at least twice a week for a few weeks I told him that we almost had sex but didn’t. So now he labels this as me lying to him. I’ve tried explaining that it wasn’t really any of his business because I was single but he still says I’m a liar. There have been many other occasions of him doing things like this. I have never cheated on him or been unfaithful of any sort but for some reason he labels me as a liar and I’m starting to feel like I’m a terrible person even though I’m not. Last night I actually had to block him from messaging me because he was again calling me “shady” because I miss understood a question. I’m away on holiday with my family and met up with some old friends. They’re all in their 40’s and 50’s but they have a son who is like 17. Immediately my boyfriend is jealous of him even though I spoke to this 17 year old ONCE and the conversation lasted less than 10 seconds. My boyfriend asked if I was going to meet the 17 year old and I said no because we were all going for a day out at the beach. I said no as it was different people I was going to the beach with. Apparently the was I answered was “shady”? Honestly I have no idea how my answer was shady. he starts sending me paragraphs about how my previous behaviour has been shady and he can tell when I’m lying so that’s why he think I’m not being truthful and that he “doesn’t mind if I spend time with the 17 year old just so long as I’m honest about it.” Whole time I’m sitting there thinking “wtf are u even on about I’m not even seeing him today…” also he’s 17!!! A CHILD!! Defending myself is a lost cause with him because he’s decided im a liar and nothing will change that. Sorry this all probably sounds like a load of waffle and it’s so hard to explain but yeah. Any advice on what I can do next or is this whole relationship a lost cause?