I already wasted enough time telling you that there are many. Even bands like Blink 182, Hollywood Undead, Linkin Park, Green Day, Nirvana had songs expressing drug abuse, depression and stuff like that. Peep was heavily influenced by those bands, as you also hear in the his songs:
"Lil Peep was described as making lo-fi rap, being an "emo-trap heart throb" and an "emo rapper". New York Times music critic Jon Caramanica defined Peep as the Kurt Cobain of lo-fi rap and described his music as gloomy and diabolically melodic. Lil Peep's music generally drew on both Southern rap and the angsty introspection of the rock subgenre post-hardcore. He said that he wanted to become the "New Kurt Cobain". Lil Peep's lyrical themes include topics such as depression, drug use, past relationships, and suicidal thoughts and meshes together third-wave emo, alternative rock, pop-punk and dream pop with trap music and hip-hop. A close friend and the executive producer of Come Over When You're Sober, Pt. 1 said that Peep "wanted give a voice to people that suffer from anxiety and depression, people who have been abused, bullied, and the people who were misunderstood like him. He had demons of his own and he faced those demons by creating music." AllMusic described his music as a blend of hip hop and rock influences along with trap, punk, and dream pop. He had also been described as the future of emo by Steven J. Horowitz of online magazine Pitchfork.
Before the release of his first album, he mentioned Kurt Cobain, David Bowie, Frank Ocean and Riff Raff as inspirations, and wanted to be known as the "Kurt Cobain of Rap". Lil Peep also cited Anthony Kiedis as his idol. His other musical influences include Gucci Mane, Red Hot Chili Peppers, Future, Crystal Castles, Seshollowaterboyz, Rozz Dyliams, My Chemical Romance and Panic! at the Disco. His songs have sampled such artists as Blink-182, Pierce the Veil, Brand New, Radiohead, Underoath, Three Days Grace, Avenged Sevenfold, Slayer, The Postal Service, Oasis and The Microphones."
And there you go. Emo music doesn't exist only since Peep: