These are common acronyms that can be used on social media or over texting. Sometimes they are separated or together. Nonetheless, at their full value, they mean:
These can be used to show how much you love someone and your absolute gratitude. In return, you can show how much you appreciate the person's love by saying at back and acknowledging their thankfulness.
Example of a texting conversation where tysm ilysm/yvw ilysm2 are used:
Person A: You look stunning today!
Person B: TYSM ILYSM!
Person A: YVW ILYSM2
Person A: YAS!
Person B: <3
I love you so bad. I love you so much it hurts. Can be used when talking about someone you're with and love a lot, but is typically used for crushes, hence the hurting.