My Original Music Disappears When NOT on WiFi, Since Activating Apple Music, plus other nonsense going wrong. PLEASE HELP!

So I made the mistake of activating Apple Music without reading about all the issues people are having. Now I'm stuck and want to get rid of this godforsaken curse I bestowed on my beloved iPod. (Dramatic, yes, but for the right reasons!) I literally have years and years of music on there. Including music I burned from CDs and time spent editing information and album art for. If I can't fix now I will literally never buy another apple product again.

So here's what I did:

1. I updated and activated apple music

2. Then at some point "iCloud Music Library" was turned on. Then It asked if I would like to "Merge your local and cloud libraries or replace with the cloud music" I obviously chose to merge them.

Now with WiFi turned on, I can see all my music. Turned off, there's absolutely nothing there. I have a freaking iPod. I'm not going to be connected to the internet all the time.

When I turned iCloud music library off, the only music available now is what I bought from iTunes itself. I have tried downloading all my music "to make it available offline" but now I don't have enough space for music I thought was originally there in the first place.

Another issue I have is that my Macbook, with the latest music on it, has crashed and everything is going to be erased on there. So it's not like I can just sync it if that's what I need to do. I'm currently working off a PC that has my itunes, but I haven't synced it with my latest iPod since last year.

Another issue is, many of my album art work has scrambled to other albums. For example, the Micheal Jackson "Bad" album now has a cover Mariah Carey. ***!

What I need to know:

1. How do I to get my "ALL" my music back, without having to use Wifi or downloading music "to make available offline"?

2. How do I get my album art work back to its original state?

3. HOW DO I GET RID OF APPLE MUSIC FOR GOOD?

I CAN PROVIDE SCREENSHOTS IF IT HELPS.