As you've no doubt heard, there were bombings of a number of churches and hotels in Sri Lanka on Easter Sunday. Reasonably accurate news has been a bit slow coming out, in part because the Sri Lankan government imposed a social media ban early on, but nearly 300 people were killed, and even more injured. It's still unclear what happened; Sri Lanka hasn't had much in the way of anti-Christian terrorism since the end of its civil war, and while tensions between Muslims and Buddhists having been getting quite serious, the attack doesn't make much sense as a part of that quarrel; the group now thought to have done it, the National Thowheeth Jama'ath, is an Islamic group that has in the past focused almost entirely on terrorist actions against Buddhists. It does seem to be the case that anti-Christian harassment has been increasing, but it has mostly been relatively minor.
The origins of the Catholic population of Sri Lanka are a little obscure; legends hold that Christianity was introduced in Sri Lanka shortly after St. Thomas the Apostle introduced it in Kerala in India. Portuguese Catholicism seems to have been introduced in the sixteenth century, and the formal Catholic organization of the island dates from St. Joseph Vaz in the seventeenth century. One of the Catholic churches that was bombed (two Catholic and one Protestant church were bombed), St. Anthony's Shrine, is actually quite a famous church, founded by one of St. Joseph Vaz's disciples; dedicated to St. Anthony of Padua, it is widely loved by Sri Lankans, Catholic or not. It's apparently not uncommon in Sri Lanka to find even Buddhists who are enthusiastic devotees of St. Anthony, who has a reputation as a miracle-worker, and the building is perhaps the most important church on the island dedicated to him.
The church that seems to have had the worst casualties was St. Sebastian's in Negombo, because it was heavily packed; nearly a hundred people died.
I'll put more up if I come across anything more; a lot of this information is scattered across a lot of different sources.
[ADDED LATER (4/24): The death toll from all of the bombings is now at 359.]
[ADDED LATER (4/26): The death toll has been revised down to 253. The reason for the discrepancy was the rather gruesome one that it was difficult to count the bodies because they were not intact.]