How to use the word "ripped"?

"My heart was ripped, you sewed it with your thread of love"

Improving on that, you might consider:

- My heart's fabric was ripped apart and you stitched it back together.

- My heart was broken and you put it back together.

- My heart was torn apart or ripped apart and you put it back together.

I would not use; My heart was ripped, only.

Also, bear in mind that passives are not always the best choice as usually in poetry one is looking for the strongest effect:

• You mended my torn-apart heart.

Even stronger:

- You mended my stricken heart

Cloth is ripped, paper is ripped with or without the word apart.

Generally, for an image involving the heart, we say a heart is broken but not that it is ripped. If you say ripped, you have to qualify the heart as being paper or fabric or some other material that can be ripped. Also ripped apart is stronger. It means the heart is now in two pieces, rather than one with small rip or tear in it. I prefer torn apart to ripped apart here.

Without changing the essence of what you wrote, here are some grammatical suggestions:

My heart was ripped apart but you sewed it with your thread of love. And when you saw another’s ripped heart, you asked me for your thread back; the same thread you used to stitch my heart. You unsewed.my heart, leaving it ripped again. I had seen you as a stitcher but I should have known that instead, you were a needleworker, with only a little thread but lots of needles. You used one of those needles to first stitch my heart but later that same needle pricked my heart. Hope this helps.