I've been thinking about posting this for a long time but it's so stupid I feel ashamed doing it. I've named changed for this. Basically my jealousy of my neighbour is driving me to distraction and I need to make it stop.
We're about the same age. She's far more glamourous than me, drives a nicer car, has nicer clothing and hair, has lots more friends (always having people over and parties), has an active social life, has more money. Basically she's everything I'm not. My marriage has been on the rocks for the last few years yet she has a partner who is attentive, buys her things, waits on her every need - everything my husband isn't. They're getting married soon so everything is all about how happy they are. I know all this because I stalk her social network sites almost every day.
I hate leaving the house when I know she's in - I feel like I'm being watched constantly. I've changed the way I dress so its more like her so she can't mock my clothes (I've overheard her friends slagging me off). I hate being in the garden when she's out there. I hate talking when I know she can hear me. I hate hearing them having sex through the wall.
I'm constantly thinking of ways I can make my house look more like theirs (even their house is nicer than mine). They had their garden done last year and I was so jealous I started going out late at night and spraying weedkiller over the fence late at night. I curtain twitch all the time to see what they're up to and any change at their house makes me stressed.
If I'm being honest she isn't a nice person (although it doesn't excuse my behaviour). She sabotaged our building work at the front of the house by spraying water on drying cement (didn't see her but she was the only one around when it happened). She deliberately wakes us up at night by being noisy and says things in my earshot meant for me. We aren't friendly with them at all.
I'm dreading their upcoming wedding, I can't be around seeing all those happy faces the day they get married. I've already planned to be away. I'm fretting about the high probability that they'll start a family very shortly and I simply can't be here when that happens. I think I might go insane if they have kids. I'm desperate to sell the house and get away but we can't afford it. I'm even putting off telling my husband our marriage isn't working - having to split and move out with half my belongings when I know she could be watching makes me feel sick. I don't want her to know even my marriage is a failure like I am.
I don't know who I am anymore. I'm not in a good place in my life generally and this fixation on her is making things worse. It's so simple to say 'just stop' but I can't. I have no-one I can tell all this because I'm so ashamed. I feel like a fraud for even admitting that this is an issue when in the scheme of things its very minor. I guess this is 'Keeping up with the Joneses' gone bad. Please help me. 
Thanks for reading such a long post.