Girl that last sentence is your answer, you haven't even gave in yet and you knowing that if you think about that it's not worth it at all!! Imagine if you do give in and from the jump he lied to you just for y'all to get close do not give in not even because he's still stuck on you or for the plot or for a change if he wanted another chance he'd stop trying to reach out after you been blocked him multiple times, respected your clear boundary and maybe even had a whole apology written/typed out instead of being annoying. He's really just immature, zero honesty overall total headache to be with if y'all were together and you are aware of how insane he looks, you can't be manipulated you are strong girl and that's great he's just stuck because he couldn't get through you with all that manipulation and relentless lying truly you are above him let one of his "girlfriends" have him
as another commenter said definitely looo into reporting this as harassment. you’ve made it painfully clear from the get go you’re not interested and he’s still relentlessly going. don’t give this guy a chance - he doesn’t GENUINELY love you, all his feelings are deep rooted in selfishness and about how he feels. every step he’s taken to get closer to you it’s clear he’s only thought about and considered how it effects HIM, no concern at all for you. if you did end up dating him as you said it would end horribly, I recommend opening up about this to family or close friends, someone you can confide in and together sort out filing a police report on this guy, screenshot everything while you can as he might try to cover his traces when he catches on/realises. I hope everything goes well for you in the end and that creep leaves you alone ( ̄∇ ̄")

Imma vent here a lil lmao feel free to criticise or advice me.
Im currently in a similar situation. Well, not an exboyfriend, but ex best friend. Yk how it is when a girl gets close or too kind to a guy. They ended up catching feelings. I was lowkey at fault too for leading him on. But then I made it clear that I can't accept his feelings when he confessed. But this guy just doesn't give up.
See, if he was a normal, ordinary guy, that would've been sweet, hell, I might actually fall for him for that. But, he's a bit cray-cray. Obsessive and possesive. Most of all, manipulative. And no, please. Obsessive and posessive guys aren't the dream red flag you'd actually want. THEY'RE CALLED RED FLAG FOR A REASON. He tells off the other guys I talk to or befriend with, constantly played the victim card to gain my sympathy (back when I just stupidly gave in), spread rumors about us HIMSELF then told me someone else started it and etc. (Bru he even went as far as lying about his family, saying they're in a bad situation just to get my sympathy and comfort him. I hate how that was the reason we got close) All that just to isolate me from others and manipulate me into accepting him in my life. Thankfully, they never really worked (I've got quite a strong reputation afterall lmao not to brag, so everyone was pretty much on my side). Since nothing worked, what did he do? He started talking and bragging about his 'relationship' with other girls to me, just to get me jealous. But the thing is, I really don't give a shit, and it only turned me off. In fact, that gave me an excuse to distant myself from him, saying I shouldn't be close to him since he's got a 'girlfriend'. Lmao, i could tell he regreted that immediately. I remember being constantly anxious because of him (not anymore though, now I just thought this situation is funny). But I managed to get away from him to pursue my studies overseas, so he has no other way to reach me but through online platforms. Mind you, blocking DOES NOT work. If I block his number, he'll use another, and another and another. EVEN HIS BUSINESS NUMBER. The same goes for all social media accounts. At one point, he'll even start bothering my friends to get his message to me through them which is what I want to avoid most. I dont want other people involved in this. So my best option was to just ghost him. I mean what could he do? It's not like he could find me for the next few years (Hope i dont jinx it.) And hopefully by the time that he could, he'd already gave up. This has been going on for over 3 years, and it's been over half a year since I ghosted him, and he never gave up. Sending unreplied messages, wishes, pleadings, etc. So yeah. Im ngl, there are times where i thought of giving in, yk, just to see how it really goes. Giving him a chance and all that but thinking about how to get away from him if anything goes wrong immediately turns me off