Being blunt here
I think when you’re on your own, it can be easy to get over involved and invested in other people and their lives and problems. I have been guilty of this in the past so am not approaching from a judgemental perspective, it is merely observational. I think this is where things can happen very gradually and it does help to take a step back.
I would agree it isn’t appropriate at all to be texting a young girl with additional needs about a relationship. It’s not because you personally pose a threat but it is because it suggests to the girl that texting adults in this way is normal, is what you do. And this then blurs the boundaries for other interactions. It puts you both at risk, and the fact you don’t see this does suggest to me that you’ve lost perspective a bit.
This next bit is harsh and I don’t like typing it but I think you need to see it. I think you believe these people are your friends and they are not. I think they’ve been laughing at you for a long time. That’s on them and not you and it’s a horrible and wrong way to behave but I do think some of your actions have crossed over a line a bit and that’s in turn led to the situation.
About seven or eight years ago I had a friend (she still is a friend) who was experiencing marital difficulties and it is a very long story but when I look back I see that I definitely became over invested in ‘helping.’ Early in 2016 I had what seemed at first to be a minor injury which turned into a major injury and chronic pain. A few months down the line, following a lot of anguish, pain, waiting, crying, hanging on to my job by the skin of my teeth, I was not only lonely but isolated through my pain and it was constantly brought home to me how vulnerable I was.
When life is like that it’s very natural to look outside of yourself for distraction purposes. A caring nature is a good thing but it’s easy to become too involved and see yourself as a bit of a knight in shining armour and I think that’s what you’ve done. You say you’re the only one who can get the DD to school but you also say she’s manipulative. Think about that for a moment.
I think you have subconsciously replaced a relationship with your friend and that’s more common than people think, it isn’t sexual, it can happen with children as well where a partner dies or leaves and a child (often the eldest but not always) becomes the surrogate spouse who the remaining parent will confide in and rely on for help. In your friends case though, she’s happy to use you but sees it as needy and sad and mocks it. It’s a horrible way to behave but you really do need to step back for everyone’s sake.
I would personally just say honestly to your neighbour that you think the texts the DD sent were inappropriate and you think it’s probably best not to communicate via this way going forward and block and mean it. She is your neighbour and you want to keep things amicable but being nice, smiley and polite but cool.
It’s really easy to trot out ‘oh get a hobby!’ but actually this is what I did. I got really into creative writing following my ‘year from hell’ and while I was never going to be the next JK Rowling or anything it gave me a focus and an interest outside of other peoples lives, or rather meant that I could take an interest in fictitious characters which is harmless! So thanks to research for writing I did I ended up reading up on a variety of social and historical references which was really interesting. Anyway that might not be for you but I think if you find something that is it would help.
The above all seems a very long time ago now. I met my now-husband a couple of years later, had DS in 2020 and DD a few months ago and the lonely woman in physical and mental pain seems light years away to the mum and wife I am now (although my injury does still play up and I do get down as I’m human) but life can and does change very rapidly. Self awareness is key here though and none of what I’m posting is trying to upset, but honestly, really, don’t pursue this friendship.