Still not sure

I must admit Anal sex is not for me but my husband get's really turned on when I do it to him ! Despite having been married over 20 years he has only recently discovered the enjoyment of penetration. I felt very uncomfortable at first as it did'nt relate to my concept of straight sex but seeing him shoot his load greater than for many years I was happy to oblige his wishes. To date I have only done it with my fingers but he wants me to use a strap-on so I can do it properly (as he put's it!).We don't have one as yet but I know it's only a matter of time and I'm sure I will get round to the idea but it still seems strange.....any advice ??