When is a lie, not a lie?

I pride myself on my honesty and integrity - you can call me anything you like, except a liar, as lying is something I never do. I may withhold information, so as not to cause offence, by not responding directly - for example if someone asked me if I thought they were beautiful, and I didn't, I would fudge a response, so I wouldn't tell them a lie, or change the subject, or simply not respond directly. Similarly if I do something wrong I will always own up to it, take responsibility for my actions, and not try and blame anyone else.
When I was at boarding school smoking was forbidden, but I, and others (and I know this included prefects who upheld the "law"), used to sneak off for illicit sessions. I was never caught directly with cigarettes on me, or actually smoking, but on 2 occasions while returning I was accosted by a prefect and asked directly "have you been smoking?" (note, this is not "where have you been?" which I could respond honestly without admitting any guilt) and I immediately admitted that I had. On one occasion the other boy with me denied he had smoked and got off scot-free, while I was severely punished (and the prefect later told me that he was the one they were really after, but his denial meant they could not take further action as all they had was suspicion!), but that didn't stop me from admitting a similar offence a year later, again when asked if I had been smoking, when denial would have gotten me off, but would have been lying!
The young friend who has looked after my house 4 times now, and who I have known for 8 years, though, is the real subject of this post. Lying seems to come easily to people here - from when they will turn up, to denial they did things (when you saw them do it!), and just generally telling you what they think you want to hear. Most are "little" lies - saying they will come at 10.00 and then arriving at 12.00 (timekeeping is a big issue in all Latin countries!), but swearing blind (including swearing on your mother's life, or crying) that you didn't break something when you were seen, or there could be no-one else to blame (as you were the only person there or using that item) is somewhat different.
This year the "friend" had a drug-induced breakdown and did some damage to my house, stole some items, and "borrowed" others - but it is the subsequent lying about some of the details that I am finding very hard to come to terms with.
He lost a set of house keys (the second time he has done this) and told me in a message that this happened just 2 weeks before my return, from a 6 month absence, though later I found out that it happened less than a month into my absence! He told me a story, which he repeated often, about where he lost the keys, though the keys turned up in my neighbour's garden, a long way from where they were "lost", but he had no explanation for that, and told me his story, oft repeated, about losing them in town had been a "joke"! A couple of days ago he told me he thought he was being chased (paranoia from the drug psychosis) so jumped over the fence, and must have lost the keys then, and this was just after I left.
My front door was smashed in - his sister told me he had put a pan on the stove and fallen asleep so the family had to break in to "save" him. I know this to be a lie as he told me he went out after putting the pan on, so he wasn't in the house in any danger (no fire or smoke damage either!), but in fact they had to break in as he had lost the keys! So his sister is also complicit in the lies. A pan was damaged, too, so badly burnt that the double base was destroyed!
He told me he had used some of my clothes as he had nothing to wear, but had washed them and replaced them. however I was looking for a shirt and asked him about it (he had moved things of mine all over) and he admitted he had it and would return it, which he did along with some other shirts. I asked if that was everything and he swore it was, but a few days later I couldn't find a book (one of a 7 part series), and he admitted he had that too, and returned it with some more clothing! Again he swore that he had nothing else, but then he posts a selfie on Facebook wearing a hoodie of mine (given to me by a friend in Iowa), and when I take him to task about that he returns it and even more shirts and shorts! Again he swears blind that he no longer has any of my things.
He, his sister and his mother have all assured me that they will repay for all the damages and losses I have incurred, but it is now over 5 months since I returned and I have seen nothing, not had any indications of when the repayment might begin.
He came round to my house two days ago as though nothing has happened (had not seen him or heard from him in over 2 months) expecting to be invited in, which I refused, telling him he had to regain my trust and friendship first. I told him that what hurt me almost as much as the thefts and damages, were the lies he has been telling me, as you should not treat a friend like that. He asked "what lies?" - so I pointed out specifically the ones about the things he "borrowed" and the lost keys. He said I had all things he had "borrowed" (as opposed to those he had sold!) back, so what was the problem, and though I pointed out the numerous times he swore he had nothing more and then when I found he had, he didn't seem to think the lies mattered as I got it all back!! Similarly with the keys, he said he was trying to explain how he lost them - by lying about it! I pointed out that he lied time and again, and then said the "story" was a joke, and wouldn't even tell me the truth when the keys were found nearby - it was at this stage he admitted jumping the fence to run away from an imaginary attacker!
I told him that in all the years we had been "friends" I had never lied to him about anything, something he acknowledged, but that I was having trouble accepting his continual lying - and that he had a lot of work to do to convince me I should forgive all and accept him back as a friend. He told me he "needed" me as a friend, as I meant so much to him, not least as a father figure, so I asked him why I "needed" him, if all he did was lie and take from me? He left avowing to regain my trust and friendship, but unless he can accept responsibility for his actions personally, and stop lying to me, I am not sure that it will ever happen.