ETA I think it should be noted that the OP's husband has been diagnosed with melanoma as best I can tell; the lymph node biopsy is to see if it has spread locally. OP correct me if I'm wrong.
With that said....
I know.

It's hard to sit around and "hurry up and wait" for these things, especially when you're a "fixer" of situations, or a typical wife/mother/woman who is accustomed to "getting the job done" and "protecting" our families, etc. (As so many of us are! Of course the same thing can be said of many men, too!)
In going through something like this, really what we experience is a "loss of control", as well as a grieving process. Our loss of control comes from not being able to fix, or change the situation; and the grieving process is something we go through over the perceived loss of health and security about the future, etc. In that sense, it helps to learn about the grieving process and realize that the emotions we're feeling (shock, denial, anger, bargaining, eventual acceptance, etc.) are all normal and will fluctuate; and learn ways to help our minds relax in order to not be in a constant state of anxiety about all of this. In this way, Complementary therapies are really helpful. (And sure, medications, for some people, if that's what works for them.)
When I had cancer, medications weren't really an option for me as I was still working (as a nurse, which adds a whole other element of frustration to having cancer) and also had two young children to care for. On chemo days, I took it as I wasn't going into work, but honestly, I found it didn't help me. I also wasn't big into complementary therapies - at the time - but once I hit "rock bottom" I realized I had to change something and that's when I sort of forced myself to use my mind to relax. Fortunately my support center was helpful in that (I took meditation and journaling, and other classes) and I also found it helpful to talk to others who were going through it and counselors there. (They had services for spouses, too, recognizing that they need support as well.)
It was one super helpful counselor that helped me to understand that I needed to let go of the "staying positive" thing I'd been clinging onto so badly (and others kept ramming down my throat, it seemed), explaining that can often become a burden, which it had in my case. Everyone experiences this differently. I was at a stage that several people I'd met on my journey had died.

And even patients' illnesses at work had become different and more intense to me once I got that cancer diagnosis myself. I worried my children were going to lose me, etc. It was awful. But once I hit rock bottom, there was nowhere to go but up, and once I figured out the best way FOR ME to cope, then it kind of came together - slowly. It took a long time after I was done with treatment to begin to let go of some of the intense worry. (Another way I coped was starting the cancer survivor's thread here, which has been a great source of strength/support/togetherness for myself and many others over the years.)
Maybe this is TMI and I apologize if it is. I realize you are still in the early stages. But hopefully it was helpful in some way, and maybe for others living through cancer as well. It's just hard for me to explain something like my initial post here without going into a little more detail as to why.
Again, everyone has their own way of dealing with this, and it varies greatly from person to person. In doing support type work for the last decade or so (as well as a nurse for triple that), I can say that most people can benefit from support, but others are somewhat closed off to it, and find other ways to cope (or not, I guess). I had a middle age man as a patient not too long ago who was particularly closed-mouth about everything. I'd offer to talk about his feelings but he didn't want to go there at all (and he was with us for a long time). One day he finally explained: he was just hanging on by a thread with his illness, and if he talked about it, he was going to lose it. OK, glad you explained. He was definitely more unusual than most, as most people want to talk at least a little bit. Not him, at all. Later, when he recovered, he was like a whole different person - with hugs all around and finally open. It's just that during his intense illness he was in that dark place and his way of coping was to deal with it all in his head and he didn't want anyone to remind him of it, etc. Just his way.
So I would maybe have a talk with your husband and see where he is in all this. Maybe he's coping just fine, like many, many do. Then take a look at where you are yourself. Are you frightened about his cancer diagnosis, maybe worried about the future, perhaps for the first time? If so, then it will be helpful for you to get some support, and that can come in many forms, as I've mentioned here. I think the book would be a good start. Stay off the internet and just go by what your DH's doctors say - the internet can be overwhelming and scary, and sometimes the information out there isn't up to date. Ask people not to tell you the scary stories of people who've had melanoma, unless it has a good outcome. There are certainly many melanoma survivors out there. I always tell my patients we are very fortunate to be living in this day and age where so many advances are available to us. Have faith in your medical team (as long as you're sure you've gotten the best you can) and your treatment plan. And come to realize (as hard as it is) that there are just some things that are out of our hands that we have to, at some point, accept (or we can drive ourselves crazy asking why). If you're religious, or spiritual, this is where it's helpful to say it's in God's hands, or up to the universe, etc., though it can take a while to come to that place. (Note - this doesn't equate to "giving up".) Probably helpful here to note that Prayer is the number one complementary therapy that people use the world over.
Best wishes.