What to do? :(

[kickmewhenimdown]

Have been with partner 7 years, and i have 1 child together and I have 1 ds from a previous relationship who call -d-p dad. Things have been a little bumpy for a while, nothing that I thought was that bad. Worse thing I thought was our love life taking a nose dive for the last year (ds2 is ny 13 months) but it had started picking up recently and I thought we were getting back on track.

He was using my laptop and didn't log out of facebook and so when i went on i noticed he had messages from next door neighbour and curiousity got the better of me. I looked. And then I wish I hadn't. There are over 1000 messages between them and while maybe 2/3rds are harmless what you having for tea type the others aren't. It's him basically painting my out to be a shit partner (i.e. kickmewhenimdown is away to xxxxx another town xxxxx wont be home till after 9, dont know what she does - when he knows fine well im at bloody uni doing my evening course to finish my degree) and him trying to get into her pants, asking what she wearing/to meet up/how much he fancies her. Neighbour seems to be going along with it. He's been telling her that he is only here for our son and would leave but doesn't want to see son homeless which is a crock of shit, I could afford to pay mortgage, id be poor but I would manage

I dont think they have done anything yet and I have copied messages into a file in case he deletes them. Im in a bloody quandry. On one hand I do love my partner and probably could forgive him eventually, and want to spend the rest of my life with him but on the other hand I think what a fucking fucking bastard, how could he fucking do this to us. I haven't let on that i know and dont know what to fucking do. I would have never in a million years thought he was capable of this :(

Its probably stupid of me but neighbour is a mess, looks like a junkie and had 3 of her kids taken off her, and literally one step away from being evicted. I feel ashamed that I am even feeling I have to compete with that. I dont blame her in any way though, it fucking him thats being a dick, she doesnt have any loyalty to me.

OP, these sound like seriously classy people you are dealing with here. I would imagine that if you told her you're a home-wrecking slut 'no you can't use the phone' that it would end up in a slap down scrag fest. I would friend request her on fb, send her a message that says "don't ask me for anything again. This is why:" then copy in some of her messages to your DP and hit send!! Fuck that for a joke.
As for your DP, you can't trust or respect a man that plays the victim and makes you out to be an ogre. That's the ultimate in un-manly. Give it a little while to fester and the no trust no respect scenario will turn into "I just don't love him anymore". Been there, done that, got the scars and the T-shirt.

Great, now that I've read more of this (it finally updated in mobile phone with bad reception) I see that you've all scared off the OP who might have actually needed a little fortifying and instead she got a trouncing.
Anyfucker I'm a newbie here, and I've lurked through a lot of the relationship posts and seen some bloody good responses from you that I've agreed with or would have posted myself if you hadn't. Just dont be too brutal on the broken-hearted ok?
Let's summarise:
If he hits you, leave.
If he cheats, leave.
If he's a plain old fucking arsehole, leave.
If he controls you "lovingly" he's still a twunt, so leave.

Did I miss anything?

im back. I did eventually confront him. He has said he has never slept with her and never had any intention of. (When the messages first started she has split up with her ex and was in temp. accommodation in a different town) and he stopped messaging her when she came back. (The messages do trail off around the time that she came back about a couple of weeks ago). He says he doesn't know why he did it other than for a 'laugh' and is fully ashamed of what he said, but then that could easily be because he was found out. He is still here, albeit on the sofa. He has apologised and said it wont happen again. I am going to have to go and think about how I am going to proceed. Despite being disgusted and fucking angry with him, I do still love him and he is still father to both my sons. I need to clarify Im not 'scared' of neighbours, but while the rest of us have words with people and leave it at that, they are the sort that would damage your property i.e. key your car (where its nigh on impossible to prove they did it). I would rather avoid having any of my property damaged, even if this means biting my tongue.

I can imagine the sort of neighbours you have and agree that its not a good idea to start trouble with them. However, I still think you need to set up some boundaries as she is taking the proverbial. I have stayed in neighbourhoods where people borrow from each other but there are limits to that and people only usually ask in an emergency - not about 6 times a day. I would try and be a bit more distant or cool with her and not answer the door to her. You are helping her out too much so you are in effect training her how to treat you! Be less accomodating - with young DC's you have enough to cope with. Let her sort her own house out.

As for your DP even if he hasn't slept with her he's right out of order - not treating you with any respect at all. I would have a very long think and leave him to stew on the sofa for a while yet.

NorthWitch has nailed it.