Advice..

So, I’m in a loving relationship and we have a beautiful little boy who’s now 6 weeks old. A few weeks ago, we went to visit my partners family who live quite a distance (other side of the country) everything went well at first, they have a 7ft German Shepard who is usually fine with me, however, this dog decided to turn on me and tried biting me. My partner put the dog in the other room for the few days that I was there. A couple days later, she let him out and he tried doing the same again. This has made me extremely scared of him.. and I do not even want to be in the same house as him whilst he’s there. The dog is fine with kids, and loves them. He’s apparently not normally a vicious dog, only to strangers that are intruding. But it’s met me before, and been fine with me.. my partner finds it offensive that I won’t go round there again if the dogs there, she claims she will lock him away again but I still have to get up in the middle of the night and go downstairs to get our sons bottles. Even if he is locked away, I’m still scared of him. I think it’s really unfair that my partner is willing to put me in this situation knowing full well I don’t feel comfortable. Am I being unreasonable and selfish? The dog is fine and doesn’t acknowledge me when it’s owners are around, and pretty much ignores me. But when nobody’s around, it will take its chance to pounce. I know this dog is fine with kids, but if it can turn on me, surely it could turn on a child?