There are times, you try the patience even of Job (look it up under Bible, pls)
Madwand, NEVER buy a personal piece of survival gear on the Net, especially a dry suit. Any suit, wet or dry or half way in between as it has to fit you exactly what it was intended for.
Wet Suit: in the cold times, 5mm is the norm, and yes it needs to get wet before the thin layer of water that it allows in will be your insulation blanket. in extreme cold, people have been known to use both (wet and dry) but for the time being, the wet suit should do you well. (You can also rent them from most diving shops at a reasonable price). Yes as previously mentioned, no matter what you use dry or wet (the extremities are the places where you loose the most heat: Head, Hands, Feet, so don't rent them buy them if you intend to try to stay warm in cold weather)
You mentioned a Dry Suit that you bought on line (bend over so I can kick....)
A Drysuit works on the idea that there is ZERO water coming into your suit, that will mean (hopefully) built in socks, neoprene gaskets around your wrists and your neck. NOTE! These can also be trimmed to fit as needed (by a pro). The dry suit has no insulation layers, it's job is to keep the water off of you at all costs. You layer silk underwear and super fleece as needed to build up your warmth level as the thermo gets lower. DO NOT CHEAP OUT! It could cost you both your lives.
Good now that you have that info, multiply it by 2 so you won't end up being single the hard way.
BTW: 49 degrees is not cold. However factor in the wind chill factors and you may wonder why I strongly recommend you both get proper gear....
If you intend to head out in colder weather, look up Hypothermia and the temp gradients that will give you an idea of how long you will live if the Mr.Chilly hits Mr Willy.