I thought funeral was a private event normally. If this one is going to be a private event, then whether you want to go or not is one part of the issue. The other one is if the T's family would invite you or wouldn't mind that you attend.

As far as the attendance itself, it really depends on the specific situation like what the therapy was like for you, how it ended, what was the overall relationship like with you T etc. Since I don't know the specifics, I can't suggest anything. Even if I knew the specifics, I, probably, wouldn't suggest anything, as this sounds like one of those situations where there is no right or wrong choice. You will make no mistake one way or another. I'd, probably, go just in order not to blame myself later that I missed the opportunity. I'd go and see afterwards if it resolved something for me and moved me towards closure. What are you going to lose anyway?