First, apologies for the length of this, but I want to make sure the whole story is here. I'm a 37 year old man. I've been with my partner for around 7 years and we have two children, 2 and 4. During their early years, my partner didn't get out much. So when she was finally able to go out dancing (she always loved ballroom and latin etc) I was fully supportive. She started going to local classes on Monday and Thursday evenings. After a while, she started attending social dances on a Friday night which ran from around 10pm until 12:45am. Again, I was fully supportive.
One night roughly last November, she was a bit late back (it was nearly 1.30am) so I called her phone. She informed me she was on a road not too far away. She got home and just as I was almost asleep and half in a dream state, the thought entered my head that she wouldn't go on that road to get back. So I innocently asked if she gave someone a lift home. She instantly went very defensive, which of cause caused me to be suspicious. I mentioned it the next day, but not much more was said.
A couple of weeks later on a Sunday, I walked in to our bedroom and she rather abruptly put her phone down (it was charging) and hovvered arround until I left the room. A little while later we were both downstairs, and I went up again to do something. She quietly followed me, peered around the door and watched me until I'd left the room. I obviously found this behaviour odd. So one day I got one of her phone bills (she didn't hide them) and checked, and she'd been texting her dance instructor, sometimes at late hours, sometimes several times a day. I questioned her about this and she insisted it was friendly, and the late hours were just to check she'd got home ok. The times seemed to agree with this and she did reluctantly let me see some of the texts. There was nothing odd in them.
So we agreed that she would be more open about her communications with him and we moved on.
Shortly after new year, she was late back again one Friday night and was again defensive about it. Given what we'd agreed and the previous suspicious behaviour, I got someone to follow her the following Friday.
She left the dance place with her instructor at 12:30am and sat in the car until 1:15am in a very dark place. I had them recorded. She was cold and he was holiding her hand. Most of the time the conversation was friendly, but there were a couple of parts I didn't like.
First, talking about dancing, the converstation turned to her being nervious around him. When he asked why, she replied twice "you have no idea of the effect you have on me". This was in a very soft flirty voice. A short while later, referring to him warming her hand up, she said something like "you're like an electric blanket. I wish you could warm all of me up" followed slightly later by her saying "I'd better not get any closer or I can't be held responsible for my actions."
I didn't let her know I'd heard all this. I'm not proud of having them recorded but given the result, I'm glad I did.
The next day, I didn't tell her I knew but asked her about her evening and why she was so late back. She lied, saying it finished at 12:45am, she left and 1 and came straight home. I told her that I knew someone else who had gone and she'd seem them leave together at 12:30, so where had they been. Only then (and getting cross) did she admit she'd chatted in the car to him. I asked if they'd held hands... "No". Did you flirt? "No, not at all". How long were you there for? "Around 10 minutes or so"... etc... basically all lies until I told her about the recording. An argument followed.
Over a few days, she finally admitted that if it was the other way around, she'd be furious at me, and that she shouldn't have acted in that way. I told her I didn't want her going to the classes with him, or to the social at all while I tried to rebuild the trust. For both of us.
Recently, she's had some tough news about a family member, and to help her release I started to agree (reluctantly) to her going back to the classes again. Last weekend, I was away from Friday night until Sunday evening. I told her I was nervous about it, but she could go on Friday and I wouldn't mind.
She didn't go on Friday night. However, on my return I found that she'd texted him over the weekend. I don't know exactly what was in the text because she'd deleted them, but the phone still showed that something had been sent to him. I questioned it and she told me that she decided she didn't want to go Friday night if he wasn't there. We argued again because I pointed out that she shouldn't care whether he is there or not, and I didn't want her contacting him. She said she doesn't see anything wrong with what she did, but obviously she knew I wouldn't like it or she wouldn't have tried to cover her tracks.
I got in touch with him and found out that she'd texted him Friday night and when he didn't respond she tried to text and call on Saturday.
I asked her this morning why she'd tried to contact him on Saturday and she denied she had, saying it was only Friday to find out if he was going. Again, another lie.
Now, let me stress, I don't think anything physical (other than the dancing) has happened between them, but the lies and cover ups and the car thing are enough for me. So I've told her I don't want her going to any classes or social events where he will be.
She says I'm being controlling (to be honest, before we had kids I probably was quite controlling, but then so is she and I've not been of late) I don't think I'm being at all unfair. I've talked about this with 2 close friends and they both think I've been much clamer and more forgiving than they would have been.
She genuinely seems to think I'm overreacting though - so I want to see what others think. I've tried to tell this as honestly as I can, and while it's my "side of the story" I've tried to remain factual.
I've offered a final ultimatum - stop seeing him or I leave. Am I being unreasonable.