Difficult post

This has been on my mind for ages, and I keep thinking I will blog about it, but it is very difficult to put into words.  It is my emotions about it that make it difficult, and should I write about it?

Here goes...
Three or four years ago I got a telephone call from my next door neighbour.  He told me he was struggling to get out of bed and could I go around and help him.  (What you have to bear in mind about this, before you judge me is his age.  At the time he was somewhere around 85-87-ish, I was definitely under 50 at the time.)  Now people who know me in person will know that I am what my Mum calls a "soft touch" and will help practically anyone, so I took his request at face value, and went round.  He had said the door was open, now if I hadn't been so naïve that should have set an alarm bell ringing...but I just went in assuming that he had forgotten to lock up the previous night. 
I went into his bedroom expecting to have to help him from the bed as he had asked.  As I got close to the bed he pushed the covers back....me still thinking things were as the seemed on the surface...however I was shocked to find out he was exposing himself, and then he asked me to "relieve" him.
I'm sorry this is very difficult to write about.  Needless to say, I left quickly.  I was so shocked that he could have been so devious and act as he did.  This neighbour had been accused, and found innocent of making sexual advances to three young girls who used to live close by, and at the time everyone presumed because the girls sometimes embroidered the truth as young children do, that they were lying about this.  They had moved away because of the court case, etc.  I now found myself in a position where I wasn't sure if anyone would believe it of an old man, and I phoned their Mum and told her what he had done, and that I was sorry that I ever doubted the girls.
A couple of days later he came to my front door and apologised for his actions, but the incident set me on my guard.
Last year after a conversation with another neighbour, I found out that he had made indecent suggestions to her whilst her husband was in hospital. 
Since then I have felt even more uncomfortable around him.
He keeps knocking at my front door with the flimsiest of reasons, and I have since a couple of weeks back, started to ignore it, if I know it is him.  (Again, if you know me, that is against  my nature.)
My reason for this is, a few weeks back he went into hospital, his son and daughter-in-law brought him home, yet shortly after they left he was knocking on my front door, I'd had a bath and was ready for bed.....the day had been very warm...yet he asked me to go round and put is central heating on.  Another neighbour who knows him well was actually outside doing something at his car, so I said "No" and suggested he ask the other neighbour, he had the cheek to ask me why, and was quite nasty when I said that I was going to bed soon.

As I've said he keeps knocking with flimsy excuses.  This man makes me feel very uncomfortable, despite his age, and then I get annoyed with myself, but I honestly do feel threatened by him.

It isn't nice to feel like this about someone who lives so close to your own house.  I wish I knew a way of making myself feel not so bad.