Interfering ex who wasn't ever really my boyfriend...

It is complicated, although we never dated, we acted like a couple. We went our separate ways and stopped talking about 5 months ago. I'm with someone else who I love to death and I'm hoping to marry and give the V card to. And out of the blue when life is fine and great I get a text. Wasn't a contact so I asked who it was and he identified himself and proceeded to strike up a conversation about how he misses me, wants to be FWB, and apologized for us falling apart. I told him that I was with someone and he didn't care. I used to care about him a lot but he got really embarrassed when his friends found out I was 9 years younger than him and when we talked about sex he would insist that he wanted to take my V but every time we went to do it something came up out of nowhere. so I'm pissed with him and he won't go away. And to make it worse he lives four streets down from me. How do I get rid of my not technically ex boyfriend??? I don't want to ruin the relationship I'm in because I am 110% committed to my current boyfriend. Advice???