I've suspected for some time now that my girl is cheating.

The usual signs... Phone rings but if I answer, the caller hangs up. My girl has been going out with the girls a lot recently although when I ask their names she says, "Just some friends from work. You don't know them."

I always stay awake to look for her taxi coming home, but she always walks down the drive although I can hear a car driving off as if she got out around the corner. Why? Maybe she wasn't in a taxi?

I once picked up her mobile phone just to see what time it was and she went berserk and screamed that I should never touch her phone again and asked why I was checking up on her.

Anyway, I have never breached the subject with her. I think deep down I didn't want to know the truth but last night again she went out and I decided to really check in on her.

I decided that I was going to park my X5 next to the garage and hide behind it so I could get a good view of the whole street when she comes home. It was at that moment crouching near the left headlight of my X5, that I noticed a slow drip of coolant coming out of a small crack in the radiator.

Is this something that I can fix myself or should I take it to the dealer?