In order to finish the song lyric, maybe you should take a good look at what you've written and figure out what the song is about, where the central image or title is, etc. Once you've done that, the way forward will become clearer.
For example, the lines that stand out the most for me in your first verse are the first three lines and the last one:
I've spent all my time with you... etc.
I'm a fool in love with you
One thing I like about your first verse is that you have 7 lines, an odd number, which gives it an unbalanced feeling that fits the "fool in love" idea. I don't think your first verse is finished yet, however. It's just a first sketch. Work on it some more.
To me, the central image that everything builds towards is the last line, "I'm a fool in love with you". Why not accept that as the title and central image of the song? It feels kind of like one of those slow, jazzy torch songs that you might hear in a retro night club. It's got built-in atmosphere. I can just see the cigarette smoke curling up towards the lights and the bimbos on bar stools holding cocktail glasses with little maraschino cherries in them.
If you accept that, then write another verse on the model of the first one, perhaps beginning with something like:
I gave you everything I had
Only to find you've been giving it back
To someone new
And ending again with the title line:
I'm a fool in love with you
That's two verses, and I can stand to listen to this structure happening twice without getting bored, but after that I want to hear something new, something different, but what?
It looks like the structure that's emerging for our little torch song is A-A-B-A, which fits the retro feeling perfectly. But what to do for the B section?
Maybe take off on the "fool" image and start with a line like:
Like a fool I had to believe you
When you said your love was true
Da-da-da-da, etc. you write the rest
Corny, but might work to go in that direction. You need at least four lines here, maybe six. Use a rhyme scheme different from the verse. Maybe have a couple of very short lines in this section. Make it look different on the page than the verse.
Then go back to the A section for the last verse. You could repeat the first verse, if it ends up being a memorable enough lyric to be repeated, or you could write a new part based on the form of the A section.
Good luck with it!
