Is there something wrong with the bike as it is now? Unless you have the knowledge, skill, tools, and money, the conversion process *can* become long, slow, and expensive. Just a cautionary note. If you are looking to get into riding more, it might be best to save the conversion route for later on. I just wouldn't sacrifice my(your) only functioning bicycle to begin a SS conversion process. But...maybe you have a stable of bikes...I just don't understand why one might want to convert a working, geared bike to a so-so single speed, unless they have some other geared bikes and this will be a townie/grocery/bar bicycle.
You mentioned the front wheel is "trashed." What does this mean? Out of true? Broken spokes? Broken hub spoke hole?
Can you boyfriend help at all with this process? Is he a skillful bicycle mechanic? If not...maybe time to find a new one
From what I gather, that bike is a rather low-end, older road bike. Buying colored, pre-built deep V rims laced to a decent hub could be expensive and a bit like lipstick on a porcine friend.
I'm also confused about the hub/axle fit on the fork. You mean the fork is not wide enough to fit over the axle washers and seat onto the axle? On a steel frame pulling the fork out just a bit really isn't a big deal.
And, if you are already at a "dead end," I foresee a long, difficult conversion process. Spacing your hubs/axles/wheels could be the least of your worries. Just wait for all the small part sizing, thread types, and sourcing parts. That is when the fun really starts.
And also, what do you mean about "courage" to ride fixed? If you can ride a bicycle well enough, riding fixed just takes a minor alteration of legs, brain, muscles. I would say though that if you are not a somewhat regular or avid cyclist, pedaling all the time, up hills and down, might not be as fun as it seems. I'm just saying if you legs aren't in cycling shape, you might want to ride a geared bike for awhile.
Not telling you what to do, just giving my opinion. it's your bike and your legs. Enjoy.