I understand there was animosity when the Republic of Ireland was created, the British got over it.
Eh, we got kicked out of the Commonwealth for it as they didn't allow republics at that time, but we didn't really take part at that point so nobody much cared. It wasn't that acrimonious.
Unless you actually meant to refer to the creation of the Irish Free State, which was a negotiated settlement
between the leaders of the IRA and the British government, one which came after two years of war, and one which forced the IRA to renounce their loyalty to the revolutionary Irish Republic and agree to remain part of the British Dominion. The result was a brief civil war, the creation of a second Irish nation marred by discrimination and violence for most of its history, decades of governments seeking to undermine the British Dominion to allow Ireland to leave and become a republic, a campaign of economic warfare, and a long-term relationship of animosity and distrust between the governments of Ireland and the United Kingdom that has only been resolved in the last 20 years.
is right, you need to stop posting comparisons to historical events because they are increasingly undermining the point you're trying to make.