For this sort of desease there has been a cure for a long time now...As long as you own the game it's ok...Just google a bit.
BTW, I have seen a 'Green Pepper' DVD today, a pack with SH3, SH4, SH5 for only Euro 13.99 ...but...with U-Play... But as said you can get rid of it.
If I'm not wrong, if you install the TWoS megamod you can bypass U-play and the campaign will advance anyway, as soon as you read the 'red messages' in TWoS warning you about campaign end simply switch off U-play and go on. You should then land on the campaign selection screen where you continue the game with a new campaign.
...Or wait for me publishing my 'Campaign Switch' mod - it still needs some refinements before release and it will bypass U-Play or any sort of...hum, I better stay polite ...