Someone is texting a person they still love, and the feeling hurts more than it ever has. The opening lines make a quiet, painful point: only one of them is crying, and it isn't the person being addressed. The speaker is the one left with the sadness, and the poem never says why they are apart.
What stands out is the repeated phrase "bittersweet feeling." It first appears as something sore and constant, then returns at the end with a clearer meaning. The speaker is glad they "didn't break" the other person, which suggests they held back or protected them somehow, yet the love hasn't gone away. Even a train is enough to set off tears, so ordinary things now carry the memory of this person.
The mood is raw, tired and honest. The plain lowercase language and missing apostrophes make it sound like a late-night message, as if the speaker is simply saying what hurts without dressing it up.