Trump’s Plan to Deliver Fraud Trial’s Closing Speech Falls Apart

Cohn was also gay, and when he was dying of AIDS Trump dropped him like a hot potato.

From your same wiki link:

and according to Seymour's notes, Trump was the last person to speak to Cohn on the phone before he died in 1986.

I haven't found anything that corroborates your statement that Trump "dropped him".

I did find this though, which reminds me of South Park; it sounds exactly like Cohn was a customer of CumHammer Brand Management:

the AIDS Memorial Quilt describes him as "Roy Cohn. Bully. Coward. Victim."

Edit: Wait, actually, looking at one of the sources from the Wiki article, there was this bit:

Bell also doubts that Cohn’s last conversation was with Trump, who, she said, abandoned his lawyer when he found out that Cohn was H.I.V.-positive. “They were so close, they talked at least several times a week,” she said. “And as soon as he found out, he took all his cases away from Roy except for one and got new lawyers. After all they’d been through together.”

Seymour is Christine Seymour, Cohn's telephone operator, who listened in on many of his conversations. Bell is Susan Bell, Cohn's secretary.