As you stated, irony is typically featured to draw attention to a contrast, and while it can have varied uses, most of them revolve around saying something one doesn't mean or reversing some kind of expectation.
In the sentence you gave, the idea of being interested in suicide arising from personal, suicidal thoughts should not be surprising or unexpected to the reader, though perhaps not so much as to warrant the use of "expectedly". The connection is certainly interesting, and the use of "interestingly" or "interestingly enough" could work to point out the unusual circumstance. But in the end, that comes down to artistic license.
If the first sentence showed an interest in animal health care, resuscitation, or resurrection, irony would aptly describe the contrast between that and suicidal thoughts, but since the two things are closely and understandably linked, irony doesn't seem to be a solid fit.
One commenter suggests coincidentally, but I disagree, as coincidence describes "when something uncanny, accidental and unexpected happens" or when there is no obvious connection other than time.
http://thatsnotironic.com/ - Turns various definitions and pitfalls and turns makes them digestible.
http://en.wiktionary.org/wiki/irony - Basic definition that could help.
http://en.wikipedia.org/wiki/Irony#Misuse - More common pitfalls