Hi guys

I've been brought up in a very strict family where family comes first.
I'm 35 and been married for 10 years and have 3 kids. Since before we got married, on several occasions I overheard my wife saying that she's having fantasies about some of my friends and about having sex with them. This completely cut me down at the knees, felt so betrayed and took me a long time to get it out of my mind, over the years things were busy with kids and work and forgetting about the marriage. She's regularly said that she can't even remember when I brought it up in arguments over the years.

We've always told each other that we love each other but we behaved like a retired couple, tired with the kids and work...
Recently, my cousin visited from overseas, she completely opened up to him an I've never seen her like this before, it was great, like we were alive again, we went around the country together n spend many weeks together.
He then returned and all was good till she started getting obsessed with him, constant messaging, I love you, I miss you, I really want you to come back, you don't understand how much i care about you, etc...
It felt like it was getting a little out if hand an I asked her to "tone it down" a little bit.
She said she didn't realise it was effecting me butbadmitted that it could have been taken out of context and she said she will stop.
I told her that she doesn't have to stop, just to consider my feelings.

After a while, I still suspected something was going on and I checked her messages (I know it's wrong and untrusting and all that), anyway, I was right, the messages kept going, when I confronted her about them, she had deleted them and lied about them ever being there... She obviously deleted them because she knew they were inappropriate, then she denied ever writing them.
Since then, I've got a real big problem with trust.
Almost a year has passed and I still can't look at her the same way.
Recently, I suspected some more "texting" was going on so I checked again (I know, I know but when you smell a rat, there usually is one).
She writes to him about our problems but tells him that what they talk about is none of my business and I don't need to know so she doesn't tell me.
My cousin is caught in the middle, he told her at one stage that she is out of line, she apologised to him for months till he started to message him again. I can understand his position and I told him not to worry.
But inside I'm being torn, am I being unreasonable in expecting some loyalty?
She tells me I'm her #1 and best friend and she can tell me anything but she tells him that what they talk about is none of my business. Even after detailing everything in our own relationship.
I don't mind my cousin knowing, we haven't been close because we're on opposite sides of the world, but I do feel very close to him.
She's always been undermining me and putting me down in public, which is something that I don't deal with very well, and why should I?
In her defence, this is something she is trying to change, if you got a problem, take me aside and we can discuss it, she has changed a lot.
However, I find this lack of loyalty to be too much to get over.
I had a lot of close girl friends that I lost contact with once we got married and recently getting in contact with to prove to myself that what she's doing is OK. It doesn't feel right to me and I feel guilty for even talking to them. I can't she how my wife doesn't understand how I feel, when I clearly don't feel ok talking to these girls knowing how it would make her feel.
She has never been a very social person and it's her way of getting attention and being accepted.
I always encourage her to go out with her friends, to go shopping while I look after the kids but that's not her scene. I can understand that she needs attention but where do I draw the line? It's not getting the right type of attention.
I don't want to tell her to stop, I just don't understand why she keeps doing this when she knows how it makes me feel.

Is it ok?
Is it still ok, even though she knows how I feel about it?
Am I being a paranoid?

Please be honest.